The Majadahonda offensive soon ended, and the Nationalist forces switched the focus of their assault on Madrid to the southeastern front along the Jarama river. Pavlov's brigade was transported through the city to the new front, and broken up into small company sized detachments to reinforce the Republican lines. As the French had found in World War I, the precense of tanks provided a strong psychological reinforcement to demoralized infantry, and there was great demand for tank support across the madrid front. Even after the losses suffered in recent weeks, the brigade's strength had increased to 60 tanks as more crews became available and more tanks repaired. The Republican forces went over to the offensive, supported by Pavlov's scattered units.

The Soviet advisers' report to Moscow on the Jarama operation was not favorable. During the attack, there had been very poor coordination between the infantry and the tanks. There had been more Nationalist 37mm anti-tank guns present, resulting in higher Republican tank losses, nearly 35-40% in some attacks. The terrain did not favor the deployment of larger formations, seldom more than company strength of 10 tanks. Nevertheless, there were some successes. On 14 February 1937, the brigade was used in a more concentrated form and in a counterattack with the 24^th Infantry Brigade, overcame a major Nationalist force, leading to the loss of about a thousand Nationalist troops killed or wounded. The brigade's units were concentrated again in late February for the assault on Pingarron, and once against, the tanks supported the International Brigades. On 27 February 1937 alone, the brigade launched 5 attacks on Nationalist positions, but took very heavy losses from Nationalist anti-tank guns in the process. In one attack alone, Nationalist artillery destroyed eight tanks, leading Soviet artillery specialist Komkor G. I. Kulik to sarcastically remark that the anti-tank gun could sweep the battlefield of tanks the same way that machine guns swept it of infantry.

In March, the front shifted yet again, this time to the north of Madrid as an Italian offensive began at Guadalajara. Once again, Pavlov's tanks were called on to save the day, and transported to the new sector. During the initial phase of the campaign, Pavlov's units were used in a defensive role to rebuff major Italian attacks. On 13 March 1937, one of the few tank-vs.-tank fights took place when the Republican T-26 light tanks shot up a company of Italian CV.3/35 tankettes near Trijueque, destroying five and seriously damaging two more. There were many small unit encounters with Italian forces, and the Italian tankers soon learned to fear contact with the Republican rearguards when supported by T-26 tanks. When the Italian CTV Volunteer Corps' offensive was finally exhausted, the Republicans went over to the offensive with Pavlov's tanks in the lead. On 18 March, three Republican infantry brigades with tank support routed the lead Italian units and seized the town of Brihuega. By the end of the day, Pavlov's force had suffered so many casualties, both to enemy fire and mechanical problems, that of its original 60 tanks at the beginning of the Guadalajara fighting, it was able to muster only nine tanks to chase the retreating Italians. The Republicans were unable to exploit their victory, achieved in no small measure with the support of the tanks.

Pavlov's force received a major infusion of new equipment and manpower in March 1937 when two more transport ships arrived from the Soviet Union bringing with them 100 new T-26 tanks. This was nearly as many tanks as had been supplied since the beginning of the Soviet intervention. The main problem was to train enough Spanish crewmen to equip them. The unfavorable view held by many Soviet officers of the Spanish tank crew led to plans to recruit tankers from the better-regarded International Brigades. Since there were limits on the amount of training that could be undertaken in Spain, these foreign volunteers were sent to the Soviet tank school in Gorkiy. The first contingent returned to Spain in time to take part in the Brunete campaign in the summer of 1937.

Pavlov turned over command of the brigade in late May to Kombrig Rudoft, and returned to Moscow in June to brief Stalin and the Military Council along with a number of other prominent Spanish Civil War advisers. Due to the influx of new tanks in the spring of 1937, it was possible increase the number of tank battalions in Spain from three to four. These new units, and the demands from other fronts for armor support, led to the decision to organize three additional armored brigades in the spring and summer of 1937. Unlike the 1^st Armored Brigade, these later brigades had only a single tank battalion, and two battalions of locally manufactured armored cars. Manned by Spanish personnel, they did not have the mobility or firepower of the 1^st Armored Brigade and were not ready until late in 1937.

By the time of the Brunete offensive, the 1^st Armored Brigade had been raised in strength to its authorized level of three tank battalions, and there was a further reserve of about 30 tanks from the new battalion, bringing Republican tank strength to 129 T-26 tanks and 43 BA-3 and FAI armored cars. Under the plan for the offensive, the 1^st and 4^th Battalions with 70 tanks and 20 armored cars would support the main assault by the 5^th and 18^th Corps (one tank battalion per corps), while the 2nd Battalion with 30 tanks and 10 armored cars would support the separate offensive by the 2-bis Corps south east of Madrid.

The Brunete offensive was intended to relieve Madrid by an enveloping offensive, emanating from west of the capital to the southeast, trapping the Nationalist forces on the southern approaches of Madrid. The attack by the 18^th Corps on Villanueva de la Canada on 6 July began badly. The tank battalion advanced across an open field with the infantry from the 34^th Division following behind, but the tanks were stopped about 500-600 meters from the town by the Nationalists' two well-concealed anti-tank guns and two field guns. Artillery and air support was requested. But four more attacks failed to overcome resistance in the town. One of the German 37mm guns had been mounted in a church steeple and was credited with a dozen tanks. The town was finally taken by the 15^th Division, but the corps failed to reach its objectives during the first day of fighting. Although the 5^th Corps made better progress, it too failed its main objectives. Over the next few days, the tanks were used to support the Republican infantry in a series of small local attacks, which largely failed to dislodge the reinforced Nationalist positions. Even after committing its reserve tank battalion, by 11 July, the 1^st Armored Brigade in the Brunete sector was reduced in strength to only 38 tanks, all supporting the 5^th Corps. On 18 July 1937, the Nationalists shifted to the offensive against the exhausted and demoralized Republican forces. They proved no more able to dislodge the Republicans, and the campaign ended in stalemate by the end of the month.

Brunete attracted far more attention by Western military analysts than most other tank engagements in Spain during the war due to extensive press coverage. The inability of the tanks to advance in the face of enemy anti-tank guns was cited by many as evidence of the failure of the tank to restore mobility to warfare. Even the noted British armor advocate B. H. Liddell Hart began to have his doubts in view of the Spanish experience. Yet to other observers, the tanks had been poorly employed, and there was skepticism whether many lessons could be learned from the Spanish experience. British armor advocate Maj. Gen. J. F. C. Fuller remarked: "Battles are not won by clichés or Liddell-Hartisms" and he dismissed most of the press remarks about armor, attributing the tanks' poor performance to the abysmal tactics employed in Spain. Russian assessments of the lessons of the Brunete campaign pay little attention to the tank operations and focused instead on the poor quality of the Republican infantry, its continued inability to cooperate effectively with either tanks or artillery, and the inflexibility of the artillery in assisting in offensive operations. It was also pointed out that the sectors where the main attack was launched had an unusually high density of anti-tank guns and artillery, 26.6 guns per kilometer compared to an average of 13.8 guns per kilometer on the front as a whole.

The International Tank Regiment was the last Soviet tank unit deployed to Spain. By the summer of 1937, the Soviet Union had shipped 256 T-26 tanks to Spain for the various tank battalions. The last major shipment of 50 tanks were BT-5 fast tanks. In contrast to the T-26 light tanks, the BT-5 fast tanks were intended for deep maneuver operations, not for close infantry support. They were a license built copy of the American Christie tank, but with a Soviet-designed turret and gun, identical to that on the T-26. They were considered by the Soviet advisers to be the most modern and best tanks in Spain, and were held in reserve through the late summer and early autumn, waiting for a major opportunity to exploit their capabilities. While Pavlov's 1^st Armored Brigade had been recruited from a unit trained and equipped to conduct close infantry support, Kondryatev's unit had been raised from the Soviet Union's premier mechanized formation, the 5^th Kalinovskiy Mechanized Corps from Naro-Fominsk which had been the show piece formation for Tukhachevskiy's experiments with deep maneuver. As in the case of other Red Army units deployed to Spain, Soviet crews made up only a small fraction of the personnel in the regiment. However, the International Tank Regiment was allotted the cream of the Spanish trainees and the personnel from the International Brigades who had been set to the Gorkiy Tank School in the Soviet Union in the spring of 1937. The training of the unit, though far better than any other Republican tank unit, was far from complete. In the hopes of preserving the mechanical state of the equipment, training was limited to stationary exercises, and there were no opportunities for the unit to practice platoon or company field exercises. For many of the Soviet advisors in Spain, the International Tank Regiment was the last, best hope to display the power of tanks on the modern battlefield. These hopes would be crushed in the autumn of 1937 during the Saragossa campaign.

Since August 1937, the Republican Army of the North had engaged the nationalist forces in the Aragon region, finally capturing the town of Belchite on 6 September 1937. In early October, another offensive was planned against the town of Fuentes de Ebro on the road to Saragossa. The immediate objective was the seize the town, but the hope was that the use of the International Tank Regiment would permit a breakthrough to Saragossa itself. The attack on the town would be conducted by Gen. Karol (Walter) Swierczewski's 35^th Division consisting of the 11^th and 15^th International Brigades. The preparations for employing the tanks were slapdash and incompetent. The International Tank Regiment was given its orders at 23:00 the night before the attack, and had a hasty 50 km road march that night to the assembly area. On arriving and refueling near the front lines, the regiment learned only two hours before the start of the attack that it was to carry infantry on the tanks during the attack. This decision was opposed by the Soviet advisers as well as by the tank regiment officers who felt that it would put the infantry at too great a risk. The BT-5 was not well suited to carrying troops, and there were no experiments in doing so prior to this battle. Although the troops from the 15^th International Brigade who would ride the tanks were regarded as good troops, the infantry unit that was supposed to accompany the tanks during the attack, the 120^th Brigade, was notorious for refusing to leave its trenches. There was no infantry reserve. The mission was planned in such haste that the regimental staff had no time to conduct a reconnaissance of the battlefield, and the Spanish command did not provide adequate details of the battle area or likely Nationalist anti-tank defenses, considering such issues "trivial". This would prove fatal to the operation. There was virtually no artillery preparation since the paltry two batteries assigned the task were armed with 75mm guns captured a few weeks before with little ammunition. A T-26 battalion was supposed to be used in one of the neighboring sectors, but did not arrive in time to take part in the initial assault.

The attack began shortly after noon. The forty-eight tanks of the International Tank Regiment started the attack with a salvo of their guns, and then set off at high speed "like an express train", with Spanish infantry clinging to their sides. In the din and dust of the attack, many of the infantry fell off the tanks, some to be run over and crushed by other tanks. Crossing the friendly trenches proved more complicated than expected as the Republican infantry had not been warned, and in the confusion there was some firing between the infantry and the tanks. Once clear of the friendly lines, the tank continued to race forward, only to find that the friendly positions were on a plateau about three to four meters over the plains below. The rushing tanks were brought to a halt, and the units had to find passageways to exit to the low ground. More discouraging still, the terrain in front of the enemy positions consisted of irrigated sugar cane fields, criss-crossed with irrigation ditches. The tanks continued their rush forward, but became bogged down in the cane and water-logged soil. They began to take fire from Nationalist field guns and anti-tank guns in neighboring buildings. The advance could not press forward due to the terrain, and there was not enough infantry to hold any territory that had been gained. After exhausting their ammunition, the tanks slowly began to make their way back to the start point with little direction or control, leaving behind several tanks stuck in the mud. The tanks rearmed and were instructed to return to extract the bogged down tanks. Instead, a T-26 battalion that was supposed to be employed in the original attack was sent out with some infantry support. The attempt to extract the tanks cost a further 80 troops. In total, the International Tank Regiment lost 19 of its 48 tanks in the attack and several more damaged, and a third of its tank crews were killed or wounded.

An American tanker in the regiment wrote shortly after the attack: "Courage and heroism are plentiful in Spain and the Spanish people have no lack of it. What they need is tactics. And as for tactics, on 13 October, Regiment BT was bankrupt." In his report to Moscow, the commander of the 35^th Infantry Division exonerated Kondryatev and his unit, and placed the blame squarely on the Army of the North commanders. With the Great Purges underway in Moscow at this time, the Soviet officers in the theatre undoubtedly thought it wise to explain their performance during the fiasco. This small battle on the afternoon of 13 October 1937 is undoubtedly the best documented of the entire war, with nearly a hundred pages of testimony being sent to Moscow by the regimental commander, his assistants, company commanders, and even several tank crewmen. Kondryatev was spared from political recriminations due to their testimony, but unlike most other major Spanish Civil War commanders, was denied the Hero of the Soviet Union decoration. He was severely wounded during later fighting in the Teruel campaign. The great expectations for the BT tank regiment had been foiled by the friction of war.

The fiasco at Fuentes de Ebro on 13 October 1937 was the swan song of the Soviet tank force in Spain. While Soviet tankers would continue to act as advisers, the number of Soviet tank crews continued to diminish and the force became mostly Spanish by the end of 1937. The Soviet Union ended large shipments of tanks after the delivery of the International Tank Regiment's fifty BT-5 tanks. In October 1937, the head of the Republican tank forces, Col. Sanchez Perales, initiated a reorganization and consolidation of the force. The four armored brigades, one tank regiment, and assorted small units were to be merged into two armored divisions. These armored divisions should not be confused with World War 2 armored divisions as they were not combined arms forces, lacking organic infantry or artillery, and were smaller. With the end of Soviet tank shipments in early 1938, the Republican army attempted to make up for the equipment shortfalls by local production. There had been small scale production of a local tank design called the Trubia since 1926, but it was an archaic design and not very successful. Instead, large numbers of automobiles and trucks were converted into improvised armored cars using boiler plate and unhardened sheet steel. Some of these were quite professional, such as those built in Valencia, but many were slap-dash contraptions with little mobility, little real armor protection, and little firepower. As a result, in may 1938 the Republican armored force had 176 tanks and 285 armored cars, and in December 1938, 126 tanks and 291 armored cars. The character of the armored force continued to shift in the direction of a road-bound force tied to the improvised armored cars as the inventory of tanks shrank due to combat and mechanical attrition. The Republic had no success in purchasing tanks from other sources except for a dozen obsolete Renault FT tanks purchased from Poland.

The last major campaign in which Soviet tank crews participated was the bitter fighting for Teruel from 15 December 1937 to 22 February 1938. The first of the new tank divisions was committed to the fighting, consisting of two T-26 battalions, the survivors of the International Tank Regiment, and other supporting units. A total of 104 tanks took part in the operations, the majority of the Republican tank force at the time. The division was not used as a unified force nor had it ever been intended to be used as such. Instead, component battalions were assigned to support various attacks. The fighting took place under difficult circumstances- extremely cold weather, heavy snow, poor roads, and in mountainous country. The tank units were praised for their efforts by the infantry they supported. While the Teruel campaign has seldom attracted much attention, it was carefully studied by the Red Army. What was striking about the campaign was that the tank force was able to function at all. By the end of 1937, the tanks had exceeded their expected mechanical life span, yet the tank units were able to maintain a respectable fraction of their tanks in combat on a daily basis and overall tank losses were modest under the circumstances- 24 tanks of which seven were captured by the Nationalists. A total of 63 tanks, more than half the force, required intermediate or capital overhaul, which was managed by the units in the field. It was a remarkable accomplishment, and reflected the growing skill of the Spanish tank crews, the maintenance units, and the tank support infrastructure created by Spanish industry. This legacy helps account for the ability of the Republican tank force to maintain its size and fighting potential for most of the remainder of 1938, in spite of the cut-off in Soviet technical aid.

A British attaché during the Spanish Civil War warned that "the greatest caution must be used in deducing general lessons from this war: a little adroitness and it will be possible to use it to ‘prove’ any preconceived theory". Certainly in the case of drawing lessons on the utility of tanks on the modern battlefield, there was a wide disparity in assessments. Armies which were already committed to the offensive use of tanks, such as the German Wehrmacht, continued their programs in spite of the poor performance of their own tanks in Spain. The Wehrmacht was not convinced that the small scale use of tanks by poorly-trained foreign tankers supporting poorly-trained militia units was an accurate reflection of the operational potential of large armored formations. Other armies were less optimistic about the future of tanks after Spain, while others simply ignored the issue. The Spanish Civil War created more controversy than insight for most armies.

To preface any remarks about the impact of the Spanish experience on the Red Army, it is essential to note the tribulations of senior army leadership at this time. In June 1937, shortly before the Brunete operation in Spain, Stalin began his purge of the military leadership with the arrest of Mikhail Tukhachevskiy and a number of other senior military leaders. The rationale for these destructive purges remains controversial but the effect was not only to destroy the generals but "also their policies and prestige". Tukhachevskiy had been the Red Army's primary architect of its large armored force and its primary proponent of offensive deep battle doctrine. His execution, and the execution of other officers associated with these programs such as the head of the Auto-Armor Directorate, I. Khalepskiy, hung over any discussions of the future of the Soviet armored force. The decimation of the advocates of armored warfare in the Red Army was paralleled in 1938 by a scouring out of the tank design bureaus, which claimed the lives of the design teams who had developed the T-26 light tank and BT tanks used in Spain. In addition, many of the veterans of the Spanish Civil War came under suspicion for possible Trotskiyite contagion and were executed, including the military attaché Gorev who had been so instrumental in the defense of Madrid. In an atmosphere of paranoid suspicion, an honest opinion publicly expressed about the potential for tank warfare or tank technology could prove fatal.

The Red Army had authorized a new set of field regulations, PU-36 in 1936. It was hoped that the Spanish experience would help to amplify and correct the field regulations, and the Intelligence Directorate of the Red Army not only collected data from the Spanish theatre for this purpose, but tasked some of the unit commanders with comparing their understanding of PU-36 to their experiences in the field. The first and only unit to methodically do so was the International Tank Regiment, formed in August 1936 under the command of Kombrig S. I. Kondryatev. Part of the problem with PU-36 was that it provided only the broadest sort of guidelines for tank operations and did not foresee the actual types of difficulties faced by tank units in combat. The Red Army had a wealth of reports and studies on tank operations in Spain. In general, these studies noted the many difficulties attending the use of armor. But at the same time, they duly noted the strained local circumstances, and the significant contribution that tanks had made in bolstering the very shaky performance of Republican infantry in many battles. The poor training of the Republican tank crews, particularly in the 1936-37 fighting, was often mentioned. As a result of the Spanish experience, as well as field exercises, the General Staff began the preparation of a series of reports which amplified PU-36's coverage of tank tactics.

The most thorny tactical problem in Spain was cooperation between tanks and infantry. In most cases, it had proven to be difficult if not impossible to accomplish. Many of the Republican infantry units had poor morale and little practical training, and would simply refuse to accompany tanks into action. Even the usually stalwart International Brigades found it difficult to operate in unison with tanks. Seldom if ever was there any training or instructions in such tactics for either the tank crews or the infantry formations. There was no established procedure for communications between the tanks and the infantry, and neither had effective tactical radios. The slow walking speed of the infantry and the much higher speed of the tanks in cross-country travel was also a problem, since once battle was joined, the tankers tried to use the speed of their vehicles to avoid being hit by Nationalist anti-tank guns and field guns. As a result, infantry units and their supporting tanks usually became separated. The tankers expected that the infantry would assist them in locating their main adversary, the concealed anti-tank gun. But even if the infantry did locate and identify the anti-tank guns, there was no reliable means to communicate this information to the tankers.

The poor level of training of the mixed Russian/Spanish crews did not foster much tactical innovation. For example, the use some of the tanks in an overwatch position to deal with the anti-tank guns, or the defense of the tanks against anti-tank guns by the use of artillery or mortar-fired smoke were seldom if ever attempted. The fighting in Spain led the Red Army to abandon the practice of tanks firing on the move since it was felt that this was ineffective and a waste of ammunition. This was an important shift in tactics and paralleled similar German tactics of the time. However, the British Army, lacking the Spanish experience, continued in this practice, much to its detriment in the tank fighting in the early years of World War II.

The coordination of tanks on the battlefield had proven far more difficult than expected. The Red Army provided only about one tank in three with a radio, allotting them to the company commanders and battalions commanders and sometimes to platoon commanders. The radios were nearly useless when the tanks were moving due to their fragility, the difficulty of keeping the radios tuned to the proper frequency when moving, and the vulnerability of the "clothesline" antenna to damage. The lack of reliable radios made it almost impossible to conduct operations above company size since units could not coordinate their activities once the battle had started. The prescribed method of communication within the platoon and company was the use of colored flags. This method proved not only useless but also dangerous. The flag colors were easily misidentified under all but the best lighting conditions, and using the flags made the platoon commander readily identifiable and vulnerable to enemy fire. The use of flags was abandoned almost immediately by Arman's group in the autumn of 1936 and not widely used afterwards. In its place, the crews were told to keep an eye on the platoon commanders tank and to follow his example. Platoon commanders generally led the three-tank unit into action, and so as often as not were the first put out of action by enemy fire. Soviet tankers' training was not entirely satisfactory, to say nothing of the Spaniard's training, and Arman noted that crews seldom showed any initiative once commanders were lost.

The inadequate communications of the tank battalions was one of the root causes of the difficulty that tank units experienced in coordinating their actions with friendly infantry and artillery. If cooperation between tanks and infantry was poor, it was essentially non-existent between tanks and artillery. The lack of direct radio communication between the tanks and the artillery meant that it was impossible for the tanks to receive fire support against their most deadly enemy, the anti-tank guns. The tank radios seldom operated well while the tanks were in motion, and at longer distance, Morse code had to be used for which there were few trained radio operators.

Red Army theorists did not immediately reject the concepts of deep battle or of large mechanized formations in the wake of the Spanish experience. Judged against the inflated expectation of armor theorists such as Fuller and Liddell Hart in Britain, the performance of tanks in Spain may not have seemed impressive. But many judgements in western Europe were based on the very incomplete press accounts of the use of tanks in Spain. There was a popular simplification in the press, sometimes promoted by extremists in the tank warfare debate, denigrating the tactic of using "penny packets" of tanks for close infantry support as antideluvian in contrast to the bright shining future of massed tank formations. This false dichotomy cloaked the real debate. All successful armies continued to use armored vehicles for close infantry support throughout World War 2 whether in the form of the Wehrmacht's Sturmgeschutz battalions, the US Army's independent tank battalions, or the Red Army's SU-76 regiments and separate heavy tank regiments. The real debate was over how much of any army's armored strength would be divided between these different roles. Secondly, there was no consensus amongst armored force advocates over whether large mechanized formations should be used to achieve the breakthrough during offensive operations or whether they should be held back until the breakthrough was achieved by infantry, supported by tanks and artillery, and then deployed in the exploitation phase of the operation.

The Red Army's lessons of the war in Spain were summarized in a 1939 study. The study began by noting that lessons of the war in Spain were important since all modern combat arms had participated in the fighting and the results were likely to be absorbed by all modern European armies. Specific tactical lessons of the conflict were highlighted including the need for the support of infantry attacks by tanks, the need for coordination between the infantry, armor, and artillery, and the vulnerability of tanks to anti-tank defenses without such coordination. In regards to the use of tanks in the defense, the report singled out the role of tanks as a key element in carrying out local counterattacks based on several examples of the 1^st Armored Brigade in 1937. The study was extremely cautious is drawing any lessons about the use of armor in deep battle since there were no experiences of the use of large armor formations in Spain. The report was skeptical about the possibilities of using independent tank groups to achieve breakthroughs in the face of well prepared defenses. The General Staff view was that the full potential of tanks had not been displayed in Spain and that the Red Army should continue to pursue plans to use tanks, but on a mass scale, with full artillery support. Georgiy Zhukov's successful use of mechanized formations in his defeat of the Japanese Kwangtung Army at Khalkin Gol in 1939 further reinforced the advocates of armored warfare.

The Red Army reorganized its tank force in 1938, enlarging the four mechanized corps and renaming them as tank corps. In addition, many of the scattered tank battalions and regiments were consolidated into 25 independent tank brigades, and efforts began to expand tank platoon strength throughout the army from three tanks to five. This last change was a direct consequence of the Spanish experience. The five tank platoon was introduced due to a string of reports from Spain complaining that the three tank platoon was too weak to carry out most tasks.

The importance of the tactical lessons for the Soviet armored forces drawn from the Spanish experience should not be exaggerated. Prior to the Polish and Finnish campaigns, Soviet studies of future tank warfare tended to employ examples from World War I tank fighting to establish combat norms, since the Spanish examples were on such a small scale. After the commitment of substantial Red army tank units to combat in Poland in September 1939, in the Far East at Khalkin Gol, and against Finland in December 1939, the focus shifted to lessons from these campaigns and the Spanish experience was pushed into the background. For example, during the 28 December 1940 meeting of the Military Council on the utilization of mechanized formations in contemporary offensive operations, chaired by Spanish Civil war veteran, Gen. Col. D. G. Pavlov, there was no mention of the Spanish experience while more recent campaigns involving armored vehicles including Lake Khasan, Poland, and Finland were discussed.

If some tactical lessons from Spain had been appreciated and acted upon, many had not. Spain highlighted the lack of durability of tank designs of the 1930s and the need for expanded technical support within the armored units. This was not acted upon, due to inertia in the industrial ministries from the paralyzing effect of the purges as well as Army inaction and complacency. The level of spare parts availability remained chronically low, and the level of technical competence of the burgeoning officer cadres was inadequate. As a result, the technical status of the Soviet tank park reached appalling levels by the time of the war's outbreak in June 1941. The T-26 and BT tanks, which still made up the vast majority of the Red Army tank park, had engine reserves on average of only 75-100 hours and about 29% of all tanks were in need of capital overhaul, that is, factory rebuilding. The result was that in 1941, far more Soviet tanks were lost to mechanical breakdown during road marches than in combat.

Calls for better training of tank crews also went largely unheeded. While the traditional view has held that the Red Army's poor performance in 1939-41 was due to the lingering effects of the purges, recent studies have begun to explore the broad range of difficulties of introducing novel technology and novel tactics into large armies dependent on conscripts and poorly trained reservists. In the 1941 campaign, Soviet tankers displayed a poor level of training and divisional records are replete with references to their inability to carry out simple functions such as driving the tank, operating the gun, or carrying out basic maintenance duties.

Of critical importance to the viability of large mechanized formation, the issue of command and control went unaddressed. This was in part due to the backward state of Soviet radio technology compared to German or American radio technology at the time. Although steps were taken to develop a new generation of tactical radios durable enough for armored vehicle use, they were not generally available until well into the war years, and even then in small numbers. It is no surprise that one of Germany's prime architects of its armored force, Gen. Heinz Guderian, was a former signals officer. The importance of radios in particular, and command and control in general, remains one of the most inadequately studied issues of the development of armored warfare in the inter-war years.

The single greatest failure of the Red Army in assessing the Spanish Civil War experience was in the area of tank-infantry cooperation. It is difficult to find any of the Soviet after-action reports from Spain that did not begin with the lament that "tank-infantry cooperation was poor". Soviet tankers held a very negative view of the average Spanish infantrymen, and this jaundiced view led them to discount the problem of tank-infantry cooperation, presuming that the situation would be better when operating with Red Army infantry. As was so evident in Finland in 1939-40 and in the opening phases of the war with Germany in the summer of 1941, this problem was not confined to Spain. The Red Army ignored institutional reforms to increase tank and infantry cooperative training and ignored the needs for improved communication between the tanks and infantry.

If Soviet tanks were not prepared to cooperate with infantry in small-unit operations such as Spain, they were even more poorly prepared to conducted coordinated maneuvers during deep offensive operations. The Red Army's existing plans to employ trucks to transport infantry formations during deep operations was shortsighted given the poor cross-country capabilities of Soviet trucks of the late 1930s as would be so evident in the Finnish campaign of 1940. Attempts to move motorized infantry units forward in a timely fashion were frustrated by road congestion. While this was partly due to the severe weather conditions in Finland, it was exacerbated by the lack of cross-country capability of the Red Army trucks. Recognizing this problem, Germany at the time was developing its panzergrenadiers and the US Army its mechanized infantry battalions, using armored half-tracks capable of moving with the tanks. Infantry mechanization remained one of the singular failures of Red Army tactics in World War 2, and forced the adoption of wasteful and humanly-costly improvisations such as the use of tanks to transport troops into battle, so-called tank desant. The problems with tank-infantry cooperation in Spain could have acted as a catalyst to a debate on infantry mechanization, but the dilemma was not appreciated by the Red Army.

While the professional ranks of the Red Army did not reject the important role of armored warfare on the future battlefield, far more conservative views were held by the post-Purge leadership of the army, made up of cronies of Stalin from the 1920 Russo-Polish war such as defense minister Klimenti Voroshilov. Voroshilov was skeptical of Tukhachevskiy's bold vision of deep battle and would have preferred to break up large mechanized formations and spread out their equipment to the rifle and cavalry divisions, thereby limiting their role to direct support. Voroshilov, and others in the army saw Spain as evidence of the difficulty of operating tanks, even in short range missions, and insisted on a larger role in maneuver warfare being played by horse cavalry.

Voroshilov's opportunity to impose his view arose following the Soviet participation in the invasion of Poland on 17 September 1939. The performance of Soviet armored brigades in Poland was disappointing. The uncontested Polish invasion was the largest employment of Soviet armor until the outbreak of the war with Germany in 1941, and involved the use of two tank corps, seven independent tank brigades, four cavalry tank regiments and six infantry tank battalions, totaling 4,120 armored vehicles. Combat losses were miniscule, only 42 armored vehicles. Yet the armored force lost nearly ten percent of its vehicles in the first few days of moving into Poland due to mechanical breakdowns, ten times the level of combat losses. In a November 1939 meeting of the Military Council, Voroshilov advocated the dismantlement of the four tanks corps, and was supported in this effort by the head of the Auto-Tank Directorate (ABTU), Gen. Col. D. G. Pavlov. While Pavlov's support of Voroshilov's effort to trim the wings of the independent armored force has often been tied to his experience in Spain, the broader political context of this decision cannot be ignored, particularly the lingering effects of the Purge. Pavlov had no personal experience with large armored formations in Spain, never commanding a unit much large than a battalion. His own lack of success in achieving tactical breakthroughs using tanks in Spain may partly explain his skepticism of the use of large armored formations. But he also realized that supporting the view of Stalin's confidant, defense minister Voroshilov, was a prudent way to avoid an executioner's bullet, a fate which it should be recalled, befell his predecessor I. Khalepskiy.

One of the largely unheralded lessons of Spain was in the area of tank design. There was general satisfaction with the performance of the T-26 light tank. It was considered a robust and capable vehicle, and was especially appreciated in comparison with the dreadful Italian CV.3/35 tankette, the weakly armored and poorly armed German PzKpfw I light tank, and the Spanish army's old and worn-out Renault FT light tanks. Both of the Nationalist tank types were armed only with machine guns, and so could not defeat the T-26 in battle, and both were too thinly armored to resist the T-26's 45mm gun. The T-26 was so superior to the Italian tankettes and German light tanks that the Nationalist army offered a bounty of 500 pesetas for every example captured; the Moroccan troops showed a special talent in this regard.

The T-26's design had taken place before the Red Army had developed any experience in tank combat and the fighting in Spain revealed some significant shortcomings that had not been foreseen by its designers. It's main failing was its poor armor, and immediate steps were taken to improve this through the introduction of sloped armor on the T-26S Model 1938. Its vision devices were completely inadequate in combat. When buttoned up, the crew was limited to small armored glass viewing slits, and in the case of the turret crew, a periscopic sight with a very limited viewing angle. The crews had an almost impossible time spotting enemy targets, especially the small anti-tank guns. So the crews tended to operate with the driver's hatch and the turret hatch open for adequate visibility. As a result, 75% of tank casualties were inflicted on crews through the open hatches. Trophies from the 1939 Polish campaign provided a partial solution, with the Red Army adopting copies of the Polish Gundlach tank periscope on future tank designs.

At the time of the Spanish Civil War, the Red Army was debating the requirements for its new cavalry tank to replace the BT fast tank and a new infantry tank to replace the T-26. The Auto-Armored Directorate defined a requirement that was a modest evolution of the BT with the same gun, but with slightly better armor and improved mobility. The requirement for the T-26 infantry tank replacement was similar, retaining the same 45mm gun, but improving the armor protection. The Red Army did not see the need for a revolutionary change in tank design, but this view was not shared by some of the tank design teams.

In early 1938, the design team from the Kharkov Locomotive Plant attended a meeting of the Military Council in Moscow in which the assistant commander for technical affairs of the International Tank Regiment, Aleksandr Vetrov, answered questions about his experiences in Spain, including both the Fuentes de Ebro battle and the fighting in Teruel. The design team came away from the meeting further reinforced in their view that the ABTU requirement was misbegotten and that the new fast tank should have thicker armor to protect it against anti-tank guns better than the German 37mm gun encountered in Spain, and should have a better gun than the old 45mm "sparrow-shooter" of the T-26 and BT. The resulting tank would emerge in 1940 as the T-34, a revolutionary design which would be the benchmark for world tank design through the first part of World War 2. The T-34 replaced both the BT and the T-26, since by a fluke of timing, the new T-50 infantry tank was delayed in development. By the time it finally did appear after the outbreak of the 1941 war, it was recognized to be too expensive and inferior to the T-34. So the T-34 was deployed instead to fulfill both roles.

Recent research on the origins of the T-34 design contradicts the widely held view that Soviet weapons design was a simple conveyor belt process, with the army developing the requirement based on its tactical doctrine, and the industrial ministries and design bureaus simply obeying and turning out a precise reflection of the Army's requirement document. Had the design bureau ignored the Spanish experience and followed the army requirements, the next generation Soviet tank would have been a mediocre design more akin to the British cruiser tanks of the period. The Kharkov design bureau's actions in this case displayed a hallmark trait of successful technological innovation in weapons design- the ability to see past the current threat and base the weapon on a projection of what the future threat would resemble. Organizationally, it was able to do so as the Soviet design bureau were given a surprising degree of latitude in the design process. Their small size did not foster to the type of paralysis that affected larger bureaucratic institutions of the Red Army, caused at the time by the Purge and the lack of consensus about the nature of future tank warfare. As a result, the tank engineers were able to use the lessons of the Spanish Civil War more effectively than the Red Army itself in assessing future technological needs.

The Spanish Civil War is regarded by many military historians as a testing ground for the weapons and tactics of the ensuing Second World War. However, some caution must be using in assessing the lessons of the conflicts. The significance of the war for armored warfare tactics has often been exaggerated, often based on misperceptions of the size of the armored forces employed and the goals of the forces involved. The Soviet-led tank units in Spain never attempted to prove or disprove theories of deep battle since the units involved were much too small to carry out such army-level or front-level operations. Nevertheless, Spain did provide a number of valuable lessons in the area of technology, training, and tactics, some of which were appreciated, many of which were not.

Bibliographic Note

The primary archival source for this article was a collection of documents obtained from the Russian State Military Archives (RGVA) by Yale University and currently housed at the Manuscript and Archives branch of Sterling Memorial Library. The Russian State Military Archive Collection (RSMAC-Group 1670) deals with Soviet-German Military collaboration in the 1920s and with Soviet military participation in the Spanish Civil War. About half of the Spanish Civil War collection consists of a variety of documents including daily reports from various advisers to Moscow, reports on unit actions, and studies on various subjects related to the fighting. The other half of the collection consists of the Soderzhanie Sbornika (Digest Collection), a special document collection prepared by the Red Army intelligence directorate for senior government and army officials and consisting of reports on key battles as well as special digests of reports on specific technical subjects such as tank operations, aircraft tactics, air defense technology in Spain and so on. For example, the Soderzhanie Sbornika No. 37 (Technical Notes on the actions of Republican Tanks in Spain) prepared in 1937 was printed in eight copies including copies for Stalin, defense minister Voroshilov, first deputy for defense Yegorov, foreign minister Molotov, and chief of staff Shapashnikov. The Yale Sbornik collection is not complete, missing a run of volumes from the summer of 1937. The bibliographic citations here refer to the Yale archives notations, not the original Russian archives, since according to Yale archivists, the Russian collection subsequently has been closed to western researchers. The author would like to thank Mary Habeck and the staff of the Manuscript and Archives division for their kind assistance on this project. Many of the other contemporary reports as well as pre-war editions of Voenniy Mysl and Voenno-istorichesskiy zhurnal were found in the collections of the Lehman Library, School of International Affairs, Columbia University.

published in Journal of Slavic Military Studies Vol. 12 No. 3, Sep 1999

©Steven J. Zaloga 1999

Spravka ob otpravke tankov i bronevikov v "X" za period s 12.10.36 7.5.37, (Russian State Military Archives Collection, Record Group 1670, Yale University Sterling Memorial Library), Box 13 (hereafter Yale RSMAC). The pretense that the Soviet tankers in Spain were volunteers was due to Soviet participation in the Non-Intervention Committee. David Cattell, Soviet Diplomacy and the Spanish Civil War, (Berkeley: Univ. of California Press, 1957).

The Soviet 1929 field regulation PU-29 envisioned at least nine types of tanks, but by the mid-1930s, the Red Army had reduced this to five: the T-35 heavy (breakthrough) tanks, the T-28 medium tank; the T-26 infantry tank; the BT fast (cavalry) tank; and the T-37 amphibious reconnaissance tank.

Krivoshein's pseudonym in Spain was Mele. The forward headquarters for the tank unit in the Madrid area was set up at Alcala de Henares. Krivoshein became one of the Red Army's most experienced tank commanders. After leaving Spain in early 1938, he commanded armor units in the Soviet Far East in the 1938 fighting with the Japanese Kwangtung Army at Lake Khasan (Nomonhon), commanded tanks again in the 1939-40 Finnish campaign, commanded the 1st Mechanized Corps during the German onslaught in June 1941, and ended up a senior commander during the Berlin operation in 1945.

Arman's group is frequently referred to as a battalion in many accounts even though it was nowhere near battalion strength since his troops were intended to form the core of a Spanish tank battalion.

Arman was his adopted name; he was born Paul Tilton and in Spain used the pseudonym Greisser. I. N. Shadkov, et. al., Geroi sovetskogo soyuza: kratkiy biograficheskiy slovar, Tom 1 (Moscow: Voenizdat, 1987), p. 75.

V. Goloveshkin, "Dobrovotsi svobody", Znamenosets, No. 11, 1986, pp 18-19.

It is not clear whether the gasoline bottles were a spur-of-the-moment improvisation, or if the newspaper accounts of the arrival of Soviet tanks had prompted the Nationalists to prepare for possible infantry fighting with tanks. The use of these Molotov cocktails, so named after the Soviet foreign minister of the time, was a surprise to the Soviet tankers, and details of their construction were duly forwarded to Moscow.

These tanks were manned by mixed Italian/Spanish crews and were part of the first detachment of Italian aid which had reached Spain in late September 1936. P. Caiti, A. Pirella, E. De Lia, "The Role of Italian Armor in the Spanish Civil War", Armor, May June 1986, p. 40. The Republican tank units seldom had much contact with the German Panzergruppe Drohne in Spain. For an account of German armor participation in Spain see: Raymond Surlemont, "German Tanks in Spain 1936-39", AFV News, Jan.-April 1992, pp. 13-14; Gen. F. M. Senger und Etterlin, "Sevilla 6. November 1936: Die Panzergruppe Thoma der "Legion Condor", der General de Pablo, der spanishche Burgerkrieg und die Folgen", Soldat und Technik, No. 10, 1986, pp. 584-588.

These claims come from Arman's report on the battle. Boevoy rabote respublikanskikh tankov v Ispanii (doklad major t. Arman), (Yale RSMAC, Box 14).

George Hill, The Battle for Madrid, (London: Vantage Books, 1976), p. 85.

This included the newly formed 2^nd Company commanded by A. Voynovskiy with a further 23 tanks, 6 BA-3 heavy armored cars and 3 FAI light armored cars, plus several of the other scattered units such as Novak's group. Doklad t. Krivosheina o boevoy rabote respublikanskikh tankov v Ispanii, (Yale RSMAC, Box 14).

The Spanish pre-war tank force had about 40 Renault FT light tanks, 4 derelict Schneider CA.1 tanks, and 26 locally produced Trubia Model 1926 tanks. The Spanish tank force had seen combat in the Rif War in the 1920s. Javier de Mazarrasa, Los Carros de Combate en Espana, (Madrid: Ed. San Martin, 1977). Francisco Fernandez Mateos, "Carros de Combate y Vehiculos Acorazados en la Historia de Espana" Special supplement to Revista Ejercito, 1984. Jose Alvarez, "Tank Warfare during the Rif Rebellion 1921-27", Armor, January-February 1997, pp. 26-28.

Report from "Sancho" to "Direktor", 5 April 1937, Predstavlyayu kratkiy otchet o rabote Madridskoy gruppy za vremya noyabr 1936g.-mart 1937g. (Yale RSMAC, Box 9)

Col. N. P. Zolotov, "Boegotovy byli…Istoriko-statisticheskoe issledovanie kolichestvenno-kachestvennogo tankovogo parka Krasnoy Armii nakanune VOV", Voenno-Istorichesskiy Zhurnal, No. 11, 199, p. 76. The heavy maintenance demands of these tanks is evident from the operators manual: Materialnaya, vozhdenie, ukhod i regulirovka tanka T-26, (Moscow: Ministry of Defense, 1934).

Plan o predzaritelnikh ktogakh opyta voiny v Ispanii, 10.3.37, (Yale RSMAC, Box 10). A day-by-day account of Arman's tank operations can be found in: Svatopluk Spurny, "T-26", HPM, No. 12, 1997, pp. 24-26.

The Bolsheviks had very little practical experience operating tanks in the Russian Civil War. Steven Zaloga and James Grandsen, Soviet Tanks and Combat Vehicles of World War Two, (London: Arms & Armour Press, 1984), pp. 27-33. In 1929, a small detachment of T-18 light tanks were used for a few days of fighting with Chinese warlord forces along the Chinese Eastern Rail Line (KVZhD). M. Svirin, A Beskurnikov, Pervye sovetskie tanki, (Moscow: Armada, 1995), pp. 50-52.

This practice had begun in World War I for the same reason, namely the low endurance of early tanks and the need to carefully reserve their running hours for actual combat missions. The French army began by using semi-trailers for the tanks, later switching to heavy trucks as they became available. The same practice is widely used in many army's today since the operating costs for a tank transporter are far lower than those for a tank. Jean-Michel Boniface, Jean-Gabriel Jeudy, Les Camions de la Victoire, (Paris: Editions Massin, 1996).

Arman met with the senior members of the Military Council including Voroshilov, Gamarnik, and Tukhachevskiy on 16 January 1937. Zapis priema u t. Voroshilova 16 Yanuarya 1937g., (Yale RSMAC, Box 9).

A. A. Shukhardin, "Tankovaya brigada zashcishchayet Madrid", in: My-internatsionality, vospominaniya sov. dobrovoltsev-uchastnikov nats. rev. voyny v Ispanii. (Moscow: Politizdat, 1975), pp. 73-85.

A Red Army light tank brigade at the time had a strength of 256-267 tanks, organized into four tank battalions, and supported by a motor transport battalion and a maintenance battalion. Pavlov's brigade was organized around three instead of four tank battalions, a planned but never completed machine gun battalion, an enlarged transport battalion, and special factory support, technical repair, medical and food supplies departments. Skhema tankovoy brigady Ispanskoy respublikanskoy armii (Yale RSMAC, Box 14) At the time that Pavlov's brigade went into operation in January 1937, it had received only 56 new tanks since the original October shipment bringing the total to date to 106.

The T-26 had a crew of three: driver, gunner and tank commander.

The unit's strength was 56 T-26 tanks if vehicles under overhaul and training vehicles were counted.

Doklad Komkor tov. Kulik, Operativno-takticheskiy opyt voyny v Ispanii (Boevye deystviya na tsentralnom fronte v period s oktyabr 1936g. po fevral 1937g.): Operatsiya myateznikov pod Makhadaonda i Las Rosas s 3.1 po 14. 1 37 i kontrudar respublikantsev ot Eskorial, (Yale RSMAC, Box 15, p. 58.)

Soderzhanie Sbornika No. 9: Zapiski uchastnikov tankovikh boev u Makhadaonda 11-12 yanvarya 1937 g. (Yale RSMAC, Box 14)

Doklad Komkor tov. Kulik: Operativno-takticheskiy opyt voyny v Ispanii (Boevye deystviya na tsentralnom fronte v period s oktyabr 1936g. po fevral 1937g.): Kharamskaya operatsiya. (Yale RSMAC Box 15) p. 88.

J. P. Harris, Men, Ideas and Tanks: British military thought and armoured forces, 1913-1939, (Manchester: Manchester University Press, 1995), p. 292.

One of the most prolific Russian writers on tank operations in Spain was Aleksandr Vetrov, Kondryatev's assistant commander for technical affairs. He published numerous articles on the subject and at least two books, one of which is his memoirs of the regiment's fighting in Spain. Aleksandr Vetrov, Volontery svobody: vospominaniya uchastnika natsionalno-revolyutsionoy voyny v Ispanii, (Moscow: Politicheskoy Literatury, 1972).

In general, Spanish tankers were used as tank turret crews, both commanders and gunners. In following the practice of earlier units in Spain, most of the regiment's drivers were Soviet tankers as were all company commanders and higher staff. International Brigade tankers were usually tank commanders. Report on the Combat Use on the 13^th of October (1937) of the Regiment of BT-5 Tanks by Robert Gladnick, Commander of Tank #7, 1^st Section, 1^st Company, (Yale RSMAC, Box 14).

Sanobespechenie tankovoy brigady i polka BT vo vtoroj Saragosskoy operatsii s 11.10 po 13.10.37 g (Yale RSMAC, Box 16)

Report on the Combat Use on the 13^th of October (1937) of the Regiment of BT-5 Tanks by Robert Gladnick, Commander of Tank #7, 1^st Section, 1^st Company, (Yale RSMAC, Box 14).

Soderzhanie Sbornika No. 57: Pismo ob itogakh Saragosskoj operatsii komdiv 35 tov. Walter, 14 October 1937, (Yale RSMAC, Box 16). The details of the attack were approved by the Soviet advisers to Army of the North, as the instructions for the attack were handed over to Kondryatev by advisers Grigoriev and Leonidov, as well as the front's chief of staff, Lt. Col. Cordon.

The Nationalists also attempted to produce tanks during the war, with little success. Javier de Mazarrasa, El Carro de combate Verdeja, (Madrid: Ed. Carbonell, 1988).

Teruelskaya Operatsiya 15.12.1937-23.2.1938, (Yale RSMAC, Box 9), p. 59.

To make up for the lack of Soviet spare parts, Spanish industry produced almost 20 tons of spare tank parts, including track, wheels, and other components. Kratkiy doklad starshego voennogo sovietnik Komdiv tov. Shtern o voennom polozhenii v. Ispanii, 5.10.37 (Yale RSMAC, Box 17).

A. D. Harvey, "The Spanish Civil War as Seen by British officers", RUSI Journal, August 1996, p. 66.

V. A. Anfilov, Dorogo k tragedii: sorok pervogo goda, (Moscow: Akopov, 1997), p. 102.

The surviving records of the 1941 tank divisions on this matter are contained in: Sbornik boevykh dokumentov Velikoy Otchesvennoy Voyny, Vypusk 33, (Moscow: Military Scientific Directorate of the General Staff, 1957).

Komdiv Orlov, Assistant Director for Intelligence, RKKA Command, December 1938, to defense minister Voroshilov

Sbornik No. 113: Predstavlyayu kratkie zamechaniy polkovnika tov. Terekhina o deistviyakh tankov v Ispanii.(Yale RSMAC, Box 18), p. 19.

Steven Zaloga, "Technological Surprise and the Initial Period of War: The Case of the T-34 Tank in 1941", Journal of Slavic Military Studies, Vol. 6 No. 4, December 1993, pp. 634-646. Steven Zaloga, The T-34/76 Medium Tank 1941-45, (London: Osprey, 1994).