The Spanish Civil War became the first serious test for the Luftwaffe’s fighter aviation, a conflict that had been brewing for a long time. In January 1930, King Alfonso XIII of Spain decided to revert to an alternative electoral system. However, authorities failed to control the left wing of the socialist republican parties, whose influence in the country rapidly grew.
In April 1931, republicans won municipal elections with an overwhelming majority, and the king left the country. Alcala Zamora became Prime Minister of Spain’s provisional government, which proved weak and unable to maintain order.
A wave of pogroms swept across Spain, during which republican supporters burned and looted churches and monasteries; hundreds of Catholic priests were crucified on their church doors. This reflected the growing political and social polarization in the country.
In June 1931, a parliament was elected, with socialist parties securing a majority. Manuel Azana, a representative of the left-wing parties, became Prime Minister, while Zamora, who attempted to pursue a moderate centrist policy, was elected President of Spain in December 1931. Attempts to stabilize the country proved largely unsuccessful.
In August 1932, General José Sanjurjo staged a military rebellion, but it was easily suppressed by the authorities. In the November 1933 elections, the conservative Catholic party, led by José María Gil Robles, won. Subsequently, in October 1934, left-wing socialists, along with Catalan nationalists and Asturian miners, attempted to overthrow the right-wing government. This revolutionary attempt was brutally suppressed by the authorities, who were supported by right-wing parties, and former Prime Minister Azana was imprisoned.
Hoping that moderate centrist forces had formed in the country capable of ending the confrontation between irreconcilable supporters of left and right parties, President Zamora scheduled new elections to the Cortes for February 18, 1936. However, the left-wing Popular Front won again, securing 267 out of 351 seats, and Azana once more became Prime Minister. The situation in the country began to deteriorate rapidly.
On July 13, 1936, José Calvo Sotelo, a former minister of the conservative government and leader of the right-wing opposition in parliament, was assassinated, having been openly threatened by one of the left-wing deputies two days prior. This event served as the final catalyst for widespread unrest.
This was the final straw, and on July 18, 1936, a military rebellion erupted in twelve military garrisons in Spain and five garrisons in Morocco. Initially, the rebellion was led by General Emilio Mola, who envisioned General José Sanjurjo at the head of a new Spanish government. Among the conspirators was also General Francisco Franco, who had previously been removed by the republicans from his position as Chief of the General Staff of the Spanish army and sent as Governor-General to the Canary Islands.
As soon as the rebellion began, Franco immediately flew to Spanish Morocco, which was under complete nationalist control and held about 47,000 well-trained soldiers. On July 19, General Sanjurjo died when the plane he was supposed to take back from Portugal crashed during takeoff. From that moment, Franco, having pushed General Mola into the background, became the sole and absolute leader of the rebellion, consolidating power.
By July 22, 1936, Spain was divided. Republican control extended over the southeastern regions, including Madrid, New Castile, Valencia, Aragon, and Catalonia, as well as Asturias and the Basque Country along the Bay of Biscay coast. The Nationalists, soon known as Francoists after their leader, held the rest of the country: Galicia, León, Old Castile, Navarre, Extremadura, Spanish Morocco, and part of Andalusia, including Seville and the port of Cadiz.
The majority of the Spanish navy supported the republicans, making it impossible to transport the Moroccan corps to Spain by sea. General Franco decided to transport his troops by air, but the rebels did not have the required number of transport aircraft. Therefore, he decided to seek assistance from Germany and sent a three-person delegation to Berlin led by Colonel Bolina.
On July 26, Franco’s envoys were received by Hitler, who, in the presence of Göring and War Minister Werner von Blomberg, agreed to initially send 30 Ju-52/3m aircraft with crews to Morocco. These were intended to transport Franco’s troops from Morocco to Spain, initiating direct German involvement.
In late July 1936, a special staff “W” (Sonderstab W) was established, headed by Lieutenant General Helmut Wilberg, to organize aid for the Francoists. To maintain secrecy, two transport airlines were specially founded: HISMA (Compania Hispano-Marroqui de Transportes) and ROWAK (Rohstoffe und Waren Einkaufgesellschaft). German Ju-52/3m aircraft, departing from Dessau disguised as planes of these companies, first flew to Italy, and from there to the Moroccan city of Tetouan, meticulously concealing their true mission.
German Intervention and the Heinkel He 51
It soon became clear that fighters were needed to cover the “Junkers” aircraft transporting Francoist troops from Tetouan to Seville. Therefore, on August 1, 1936, the German ship “Usaramo” sailed from Hamburg, carrying six He-51B-1 fighters, twenty 20-mm anti-aircraft guns, and 86 personnel led by Oberleutnant Alexander von Scheele. Among them were ten Ju-52 crews and six fighter pilots: Oberleutnants Hannes Trautlofft, Kraft Eberhardt, Herwig Kschöppel, and Leutnants Wolf-Heinrich von Houwald, Ekkehard Hefter, and Gerhard Klein. All pilots were formally discharged from the Luftwaffe, wore civilian clothes, and carried documents with Spanish surnames to mask their true identities.
On August 7, the “Usaramo” arrived at the port of Cadiz, which was in Francoist hands. The He-51Bs were then transported to Tablada airfield in the suburbs of Seville. By August 11, all six aircraft were assembled and test-flown, after which they were sent to Escalon del Prado airfield in the Salamanca area, where nine more He-51Bs arrived via Portugal on August 17. All these were intended to support General Mola’s offensive on Madrid, bolstering the Nationalist forces.
Initially, German pilots only acted as instructors, helping the Spaniards master the new aircraft. On August 18, Spanish pilots Captain García Morato and Lieutenant Julio Salvador achieved their first victories, shooting down five republican aircraft. However, it soon became apparent that most other Spanish pilots had a very low level of flight training, hindering their effectiveness in combat.
For example, on August 18, one He-51 was seriously damaged during landing. On August 23, during a raid on the republican airfield of Getafe near Madrid, three He-51s covered eight Ju-52/3ms. The sortie itself went smoothly, but during landing, the Spaniards damaged two of the three Heinkels. Both aircraft sustained such severe damage that they were beyond repair. On August 24, another He-51 was shot down by republicans in an aerial battle. Thus, within a week, a quarter of the 16 He-51Bs delivered to Spain were lost, a significant setback.
Oberleutnant von Scheele, responsible for coordinating aid to the Francoists, realized that if things continued at this pace, he would soon have no fighters left. As a result, after brief consultations between von Scheele and Berlin and formal agreement with the Spaniards, German instructors were permitted to participate in combat sorties, marking a shift in German engagement.
The very next day, August 25, 1936, Hannes Trautlofft and Kraft Eberhardt shot down two republican Breguet XIX bombers. These were not only the first victories for German pilots in Spain but also the first victories for Luftwaffe fighters in general, signaling their presence and capabilities. Between August 26 and 30, Trautlofft, Eberhardt, and Herwig Knüppel shot down seven more aircraft: four Potez 540 bombers, two Breguet XIXs, and one Nieuport 52 fighter.
On August 30, Hannes Trautlofft had the dubious honor of becoming the first Luftwaffe fighter pilot shot down in combat. His He-51B-1 “2-4” was downed by a republican Dewoitine D.371 fighter. Bailing out, Trautlofft landed in an area held by Francoist forces and returned to his airfield unharmed, a testament to his luck and skill.
The first German pilot to die in Spain was Lieutenant Ekkehard Hefter. On September 28, 1936, immediately after takeoff from an airfield near Vitoria, the engine of his He-51B-1 unexpectedly failed. The aircraft, hitting a tall tower of the city cathedral with its wing, crashed and burned in the city’s Cathedral Square, a tragic accident.
In late September 1936, ten more German fighter pilots arrived in Spain: Dietrich von Bothmer, Kurt von Gilsa, Willi Goedekke, Kowalski, Oskar Henrici, Ernst Mratzek, Günther Radusch, Paul Rehan, Erwin Sawallisch, and Hennig Strümpell, further increasing Germany’s unofficial presence.
However, secret foreign military aid was not only provided to the Francoists. The Soviet Union, France, USA, Netherlands, England, and Czechoslovakia supplied aircraft to the republicans, making the conflict a proxy battleground for various international powers.
The first Soviet military advisors appeared in Spain by late August 1936. Then, in September, Soviet military equipment, including SB bombers and T-26 tanks, began arriving via third countries. The official decision to provide military assistance to the republican government of Spain was made on September 26, 1936, at a meeting of the Politburo of the Central Committee of the All-Union Communist Party (Bolsheviks). The operation to deliver equipment and military advisors was entrusted to the Red Army’s Intelligence Directorate, which was initially allocated 1.91 million rubles and 190,000 US dollars for this purpose. Subsequently, additional funds were repeatedly allocated for these purposes by special decisions of the Politburo. For example, on October 13, 400,000 US dollars were allocated, and on October 17, two and a half million rubles, highlighting the scale of Soviet commitment.
In October 1936, the Soviet Union began mass deliveries of its fighters to republican aviation. On October 13, the transport ship “Stary Bolshevik” arrived at the port of Cartagena, delivering artillery, small arms, ammunition, medicine, and 31 I-15 fighters to the republicans. On October 15, the cargo ship “Karl Lepin” arrived there with 16 I-15s. On October 16, the transport “Lava Mendi” delivered six more I-15s to Cartagena. On October 25, about fifty I-16s arrived at the port of Alicante aboard the steamer “Komsomol”. On November 1, the transport “Andrei” arrived at the port of Bilbao on the northern coast of Spain with 15 I-15s, demonstrating a systematic and large-scale supply effort.
It should be noted that the deliveries of Soviet weapons to the republican government of Spain were by no means “gratuitous aid from the Soviet people to the fraternal Spanish people fighting fascism,” as Soviet propaganda claimed. In an atmosphere of strictest secrecy, the Spanish government’s gold reserve was transferred to the Soviet Union. It was initially assumed that it would be stored there until the final victory of the republicans, and then returned to Spain. However, when the Francoists ultimately won, Moscow decided not to return the Spanish gold and kept it as payment for Soviet military equipment supplies to the republicans, revealing a pragmatic and financially driven motive.
In early November 1936, the mass appearance of International Brigades, formed from volunteers from various countries, began on the republican side. Their total strength was estimated at approximately 30,000 people. If, until then, Germany, Italy, the Soviet Union, France, and other countries had tried to maintain at least outward neutrality regarding the Spanish Civil War, now, as they say, everything finally fell into place, with international allegiances becoming fully exposed.
The Formation of the Condor Legion and New Tactics
Under these circumstances, the leadership of Nazi Germany decided to no longer conceal its aid to the Francoists. On November 3, 1936, the Condor Legion, consisting of 4,500 volunteers, was formed in Germany. Major General Hugo Sperrle was appointed its commander, and Oberst Wolfram von Richthofen became its chief of staff, marking Germany’s official and open military intervention.
Within the Condor Legion, the J/88 fighter group was formed, led by Major Hubert Merhart von Bernegg. It comprised four squadrons: 1.J/88 under Hauptmann Werner Palm, 2.J/88 under Oberleutnant Otto Lehmann, 3.J/88 under Oberleutnant Jürgen Roth, and 4.J/88 under Oberleutnant Kraft Eberhardt, establishing a dedicated Luftwaffe fighter presence.
While the units of the Condor Legion were still en route to Spain, aerial battles there intensified. On November 13, five Ju-52s led by Oberleutnant Rudolf von Moreau and three He-46s piloted by Spanish pilots took off from Ávila airfield and headed for Madrid. They were covered by nine He-51s from 4.J/88. Following them to the Spanish capital came the Italians—three Ro.37s escorted by a “trio” of CR.32s. Over the eastern outskirts of Madrid, in the Casa de Campo area, they encountered two “sixes” of I-15s piloted by Soviet airmen, leading to a major aerial engagement.
While the bombers hastily dropped their bombs and turned back, a fierce battle ensued between the fighters at an altitude of about 1500 meters. During the battle, 4.J/88 lost four He-51s, including the aircraft of squadron commander Oberleutnant Kraft Eberhardt and flight commander Leutnant Oskar Henrici. Eberhardt died when his Heinkel collided head-on with an I-15 attempting to attack a Ju-52. Leutnant Henrici had a bullet pierce his lung, but he still managed to reach Francoist territory and make a forced landing. By the time help arrived, Henrici was already dead, having succumbed to heavy blood loss. Eberhardt and Henrici became the first Condor Legion and Luftwaffe pilots killed in combat, highlighting the intensity of the fighting.
In the same battle, two CR.32s were shot down, one Italian pilot was wounded, and the other pilot was captured by the republicans. In turn, the republicans lost three I-15s. The commander of the 3rd squadron, Lieutenant K. I. Kovtun, and Lieutenants I. G. Nechipurenko and P. P. Petrov were killed. According to eyewitness accounts, Kovtun managed to jump out of his burning aircraft. However, when his parachute canopy opened, Kovtun was suddenly flipped upside down by the strong jerk, and he slipped out of the parachute harness. He probably hadn’t fastened his chest strap. The empty parachute drifted to Francoist positions, and Kovtun fell onto one of Madrid’s streets, a tragic end for the Soviet pilot.
Two days later, on November 15, 1936, units of the Condor Legion disembarked in the port of Cadiz, and German soldiers officially stepped onto Spanish soil. Simultaneously, small units of the Wehrmacht and Kriegsmarine, respectively named “Imker” (Beekeeper) and “Nordsee” (North Sea), were also sent to Spain, further solidifying Germany’s military presence.
In December 1936, four prototypes of the new Bf-109 fighter—V-3, V-4, V-5, and V-6—were delivered to the Condor Legion for frontline testing. Oberleutnant Trautlofft was one of the first pilots to test the “Messerschmitt” in combat. On December 8, 1936, he achieved his fifth victory in prototype Bf-109V3 W.Nr.760, shooting down an I-16. Trautlofft’s objective assessments, persistence, and insistent recommendations helped refine the new fighter and launch it into series production. By March 14, 1937, the first three production Bf-109B-1s had already arrived at 2.J/88, marking the introduction of a game-changing aircraft.
By October 1937, only Madrid and New Castile, Murcia, part of Aragon, and Valencia and Catalonia along the Mediterranean coast remained in republican hands. By the end of 1937, republican aviation comprised approximately 230 I-15s and 160 I-16s, a significant force but diminishing in reach.
Throughout 1938, all J/88 squadrons were equipped with new Bf-109Bs. They had superior technical characteristics compared to the Soviet I-16s and I-15s, but Condor Legion pilots could not yet fully utilize all the advantages of the “Messerschmitts” because they continued to adhere to traditional tactics, flying in “Kette” formations of three aircraft, which limited their potential.
On April 14, 1938, former 2./JG334 commander Oberleutnant Werner Mölders arrived in Spain to replace Oberleutnant Adolf Galland as commander of 3./J88. No one at the time could have predicted that this seemingly routine event would have such serious consequences for Luftwaffe fighter aviation, ushering in a new era of air combat.
During the battles in Spain, Mölders concluded that the old fighter tactics, designed for large groups of slow biplanes, were hopelessly outdated. Flying in dense “threes” with new, faster fighters, pilots had to spend most of their time ensuring they didn’t collide with each other, rather than focusing on the enemy.
Therefore, Mölders developed and began to implement a new tactic based on the use not of a flight of three fighters (Kette), as before, but a pair of fighters (Rotte) or two pairs (Schwarm). Each such pair operated in the air as an independent combat unit. Fighters maintained a distance of approximately two hundred meters from each other, providing greater flexibility and situational awareness.
This distance allowed pilots to concentrate fully on searching for the enemy without worrying about precisely maintaining the distance between their own aircraft. The leader of the pair (Rottenführer) conducted a visual search for the enemy in the forward hemisphere, while the wingman (Rottenflieger) covered his rear. In the air, two pairs of fighters took positions resembling the four splayed fingers of a hand. If one pair was attacked by the enemy, the fighters of the second pair had the opportunity to turn towards the enemy and open fire, offering mutual support and superior tactical advantage.</p
The new tactics bore fruit, and on December 5, 1938, Mölders returned to Germany with 14 victories to his credit; three more of his victories were not officially recognized. He became the most successful pilot of the Condor Legion. The tactics he developed formed the basis of operations not only for Luftwaffe fighter aviation but were later used by pilots from other countries as well, fundamentally changing aerial combat strategy.
The End of the War and its Legacy
On March 28, 1939, General Franco’s troops entered Madrid, and the commander of the Condor Legion, Major General Wolfram von Richthofen, ordered his subordinates to cease all combat operations in Spain. Franco’s army could now deal with the remaining pockets of republican resistance on its own. On May 26, the Legion boarded German ships in the port of Vigo, which transported it to Hamburg. All aircraft, with the exception of the Ju-87, and equipment were left for Franco’s army, symbolizing the end of foreign military intervention.
After the Condor Legion’s return to Germany, the Luftwaffe command established a special commission in Döberitz for awards and the organization of festivities. An eight-day “Victory Festival” began with the presentation of a special award to the legionnaires—the German Spanish Cross in Gold (Deutsche Spanien-Kreuz in Gold). In addition, all of them received Spanish awards—the Medalla Militar and Medalla de la Campaña. The celebrations concluded on June 6, 1939, with a ceremonial march of the Condor Legion through the Brandenburg Gate in Berlin, a public display of Nazi Germany’s foreign policy success.
Some time later, nine particularly distinguished legionnaires, including fighter pilots Werner Mölders, Wilhelm Balthasar, Walter Oesau, Wolfgang Schellmann, Günther Lützow, and Wilhelm Ensslen, were awarded the German Spanish Cross in Gold with Swords and Diamonds (Deutsche Spanien-Kreuz in Gold mit Schwertern und Brillanten), recognizing their exceptional bravery and contribution to the conflict.
In conclusion, the following figures can be presented. At the beginning of the Civil War, the republicans had 214 aircraft. Between 1936-39, they received another 1,947 aircraft from friendly countries, of which 1,409 were supplied by the Soviet Union, 85 by France, 72 by the USA, 72 by the Netherlands, 57 by England, and 47 by Czechoslovakia, though only the USSR and France provided combat aircraft. During the same period, 55 more I-15s were assembled by the republicans themselves. Additionally, the USSR supplied the republicans with 350 tanks, 120 armored vehicles, 1,500 artillery pieces, over 20,000 machine guns, about 50,000 rifles, several torpedo boats, and a large quantity of equipment, ammunition, and fuel, showcasing the scale of international support.
For its part, Germany sent about 650 aircraft to Spain, including 131 He-51s, 131 Bf-109s, 82 He-111s, 58 Ju-52s, 32 Do-17s, and 27 He-59s, as well as 200 tanks and over 700 artillery pieces. Italian aid to General Franco included about 1,000 aircraft, 150 tankettes, 16 armored cars, about 2,000 artillery pieces, 8,000 vehicles, about 240,000 rifles, 4 destroyers, 2 submarines, ammunition, and equipment, indicating substantial Axis assistance.
Republican aviation claimed 345 victories, with 213 by Soviet pilots, 85 by Spaniards, 23 by French, 22 by Bulgarians, and two by Americans. In turn, Francoist aviation pilots claimed 695 victories, of which 314 were attributed to the Condor Legion, 205 to Italian pilots, and 176 to Spaniards. Between 1936-39, 405 Luftwaffe fighter pilots gained combat experience in Spain: 125 officers and 280 non-commissioned officers. Of the 262 aircraft that were part of J/88 of the Condor Legion during this period, 40 Bf-109s and 38 He-51s were lost. Combat losses due to enemy action (shot down in aerial combat, by anti-aircraft fire, and destroyed on the ground during republican air raids) amounted to 21 Bf-109s and 34 He-51s, providing a comprehensive overview of the air war’s human and material cost. (c) Mikhail Zefirov. “Luftwaffe Aces. Day Fighters”