Learning the Wrong Lessons

The Influence of Tanks in the Spanish Civil War on the U.S. Army

By Maj Michael Hanson, USMC

Article published on: March 15, 2026 in the Spring 2026 issue of Armor

Read Time: < 9 mins

Figure 1. M3 Light tank going through a water obstacle, Fort Knox, Kentucky. (Photo courtesy of the United States Library of Congress)

The Interwar Period of 1919-1939 represents an era of both stagnation and innovation, where militaries around the world prepared for their own disparate visions of future warfare. Towards the end of this period, the Spanish Civil War offered a glimpse of the nature of future combat, and several nations used it as a laboratory to test equipment and ideas that would inform how they should fight in the next great conflict. Germany, Italy, and the Soviet Union all sent advisors and equipment to Spain, ultimately a proxy conflict between their competing ideologies. Other countries, such as the United States, sent observers and studied reports detailing the combat. Despite this great opportunity, the United States Army drew the wrong conclusions in tank employment from the Spanish Civil War. These incorrect conclusions stunted the development of tanks and armored doctrine in the U.S. Army, leaving the American Army less prepared for the war that would come than the Germans who came away from Spain with better conclusions on the employment of armor. This paper will examine the lessons of armored employment in the Spanish Civil War and trace where U.S. Army thought diverged from the conclusions of the Germans.

Conventional wisdom recalls that, since its introduction during the First World War, the tank has been universally known as the decisive weapon of combat on land. However, this simple narrative misremembers history. A clearer memory would grant the tank this honor only after the success of the German blitzkriegs during the Second World War. The period between the world wars witnessed great, and sometimes bitter, debates between theorists in the armies of Great Britain, France, Germany, the Soviet Union, and the United States about the role of the tank in future combat.1 These debates generally represented two schools of thought. The first saw the role of the tank largely unchanged from how it was employed during the First World War, as a direct support weapon to the infantry, a moving heavy weapons platform to reduce enemy strongpoints and enable the infantry’s advance.2 The other school saw the tank as a vehicle capable of independent action, a weapon that could penetrate the front line and drive deep beyond, wreaking havoc in the enemy’s rear.3 The U.S. Army counted proponents of both schools within its ranks, though disciples of the first school would dominate some of the highest positions of the Army even after the start of World War II.

During the interwar period, however, a vigorous debate occurred between the two camps, informed by theoretical writing, observations of other militaries, and testing of concepts and equipment in official experiments. Where each camp agreed though, was that the design of tanks had evolved since the First World War. During that war, tanks were large and slow, offering easy targets to defending artillery employed in direct fire mode.4

Interwar theory and experimentation in the U.S. Army up until the mid-1930’s had settled on lighter tanks, which though lightly armored, possessed great speed and maneuverability. American theorists believed superior mobility would offer tanks the protection they needed against enemy fire.5

When civil war broke out in Spain, the U.S. Army watched closely and continued its internal discussion. Reports from Spain soon contradicted the assertions put forth by American tank theorists. According to CPT Hayden Sears, “It had been conclusively demonstrated that the lightly armored, high-speed tank was of …. no value against an organized position, …. In fact, in all cases where Russian tanks had engaged German and Italian tanks, the heavier armor and armament of the Russians had made them superior. Power, heavier armor, and armament had come forward as decisive qualities, rather than excessive speed.”6

These comments reflected the physical characteristics of individual tanks, namely their armament, armor, and speed. The employment of tanks as units produced similar criticisms, namely that because tanks in such cases, as described by CPT Sears, had not been employed in mass but largely individually or in small groups, this method of employment allowed opposing anti-tank gunners to focus their fires on few or even lone tanks.7 Likewise, the U.S. Army concluded that anti-tank guns would serve an outsized role in future combat, and placed its importance ahead of that of the tank.8

These thoughts held stock at the highest echelons of the Army by such influential leaders as the former Chief of the Infantry and then Military Attache to Spain MG Stephen Fuqua, then Chief of the Infantry MG George Lynch, and even then, Chief of Staff of the Army GEN Malin Craig. MG Fuqua’s view was that “tanks did not prove themselves in separate offensive operations because they were effectively challenged by anti-tank weapons.”9 Fuqua was supported in his view by British and French associates who, “concluded their only value was in support of the attacking infantry.”10 MG Lynch expressed similar sentiments, believing the “accepted use of tanks had been largely discredited” by the Spanish Civil War.11 Lynch declared, “The infantry tank has just one primary mission: the neutralization of machine guns…. It has paid for itself if it succeeds in eliminating this obstacle to the rifleman’s advance.” MG Lynch’s conclusion was that “the tank is a powerful auxiliary.”12

Informed by such perspectives of high-ranking officers, GEN Malin Craig, offered the conclusion of the U.S. Army’s observation of the performance of tanks in Spain in testimony to a congressional subcommittee. He related that, “tanks were not successful due to anti-tank weapons, insufficient armor, and mechanical defects, tactical errors in their employment especially en masse, and inadequate support from artillery and tactical aviation.”13 Regarding the acquisition of new tanks, GEN Craig advocated for “a type suitable for close support of [the] infantry,” in his December 1937 dated Report of the Chief of Staff.14 Thus, the U.S. Army’s underlying conclusion from the Spanish Civil War was that the role of tanks in future war was akin to the infantry support role they fulfilled during World War I, rather than as a weapon massed to break through and push deep beyond enemy lines.

In contrast to this, the Germans left Spain with much different conclusions. Regarding the threat of anti-tank guns, German MAJ Adolf Von Schell observed that due to a lack of organic anti-tank guns, most of the world’s infantry formations could not actually halt an attack of massed tanks.15 Furthermore, he noted that the anti-tank guns the infantry possessed were relatively weak, but upgrading to larger calibers would only inhibit the mobility of these infantry formations.16 He concluded that the solution to this problem was in fact the tank itself, which could mount a larger gun while retaining mobility.17 Thus, while the U.S. Army continued to advocate for light tanks to methodically support the infantry’s advance, the German Army developed tanks with larger guns and heavier armor, designed to go head to head with other tanks and cut deep into the enemy’s rear.18 The lessons the Germans took from the Spanish Civil War manifested in the development of tanks that, in terms of firepower and protection, American tank theorists did not believe were even possible at the time.19

To be sure, there were officers in the U.S. Army that did not accept the views of high-ranking generals such as Fuqua, Lynch, and Craig. Going back to the 1920’s, Infantry and Cavalry officers like BG Frank Parker, COL Daniel Van Voorhis, and BG Adna Chaffee advocated for combined arms formations of armored vehicles to be employed in mass to penetrate the front line and attack enemy rear areas.20 They had dutifully observed foreign army experiments and experimented in armored tactics, techniques, and procedures with their own formations. The Depression era lack of resources for the military, as well as isolationist sentiments ended their experiments and severely curtailed their theories.21 Despite these setbacks, officers such as these continued to articulate their theories of the role of tanks in future warfare, though their story is beyond the scope of this paper. Suffice to say, when the Germans surprised the U.S. Army establishment with their victorious blitzkriegs, the U.S. Army quickly turned to its own armor enthusiasts like BG Chaffee to quickly correct its shortfalls and prepare for the war that was coming.22

For armies around the world, the period between the world wars was a time of innovation and experimentation, as well as one of misinterpretation and stagnation. Like others, the U.S. Army experienced its own doctrinal journey to World War II. However, during one of the best interwar opportunities to learn about the role of tanks in ground warfare, the U.S. Army drew the wrong conclusions. The Spanish Civil War of 1936-1939 represents a lost opportunity to learn about the role of armor in future warfare. Yet, during this same time the Germans took away the correct lessons and used these to improve their tanks and armored forces in preparation for their blitzkrieg campaigns only a few years later. Only the shock of the German success in these campaigns would finally awaken the U.S. Army to the great potential of the tank and armored formations. It would be a long and extremely hard fight before American armored forces bested those of the Germans.

Notes