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 clich閟 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.
Final Reinforcements
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 1st 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 5th 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 35th Division consisting of the 11th and 15th 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 15th 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 120th 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 35th 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.
Lessons of the Spanish Civil War
A British attach?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 attach?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 1st 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.