German involvement in the Spanish Civil War German involvement in the Spanish Civil War began as soon as Spanish Civil War broke out in July 1936 , Adolf Hitler immediately sent in powerful air and armored units to assist General Francisco Franco and his Nationalist forces . The Soviet Union sent in smaller forces to assist the Republican government , while Britain and France and two dozen other countries set up an embargo on any munitions or soldiers into Spain . Germany also signed the embargo but simply ignored it . The war provided combat experience with the latest technology for the German military . However , the intervention also posed the risk of escalating into a world war for which Hitler was not ready . He therefore limited his aid , and instead encouraged Mussolini to send in large Italian units . Franco ' s Nationalists were victorious ; he became an informal ally of Germany , while remaining neutral in the Second World War . The Spanish episode lasted three years and was a small - scale prelude to the world war which broke out in 1939 . Nazi support for General Franco was motivated by several factors , including as a distraction from Hitler ' s central European strategy , and the creation of a Fascist Spain friendly to Germany to threaten France . It further provided an opportunity to train men and test equipment and tactics . Military operations . Hitler decided to support the Nationalists in July 1936 . The German air force was used to carry the Army of Africa to Spain . A Spanish - German Spanish - Moroccan Transport Company ( HISMA ) and an entirely German company , the " Raw Materials and Good Purchasing Company " ( ROWAK ) were established . German transports moved nearly 2 , 500 troops from Spanish Morocco to Spain . Early intervention helped to ensure the Nationalists successes in the war ' s initial stages . The training they provided to the Nationalists proved as valuable , if not more so , than direct actions . From 29 July to 11 October the Germans transported 13 , 523 Moroccan troops and 270 , 100 kilograms of war material from Morocco to Andalusia ; and it was Franco ' s African forces , thus transported and supplied , which were a decisive factor in the war . Germany signed the Non - Intervention Agreement on 24 August 1936 , but consistently broke it . After a Republican air attack on the German warship " Deutschland " , Germany and Italy said they would withdraw from the Non - Intervention Committee and from maritime patrols . Early June 1937 saw the return of Germany and Italy to the committee and patrols , but they withdrew from patrols following a further attack . The German military in Spain , who were later reorganised and renamed the Condor Legion , claimed to have destroyed a total of 372 Republican planes and 60 Spanish Republican Navy ships . They lost 72 aircraft due to hostile action and another 160 to accidents . German aid to the Nationalists amounted to approximately £43 , 000 , 000 ( $ 215 , 000 , 000 ) in 1939 prices . German air crews supported the Nationalist advance on Madrid and the relief of the Siege of the Alcázar . The Condor Legion ' s aircraft were accompanied by two armoured units . By the end of 1936 , 7 , 000 Germans were in Spain . The Nationalists were supported by German units and equipment during the Battle of Madrid and during the Battle of Jarama of February 1937 . The fighting demonstrated the inadequacy of the Legion ' s aircraft compared to superior Soviet - made fighters . The War in the North was supported by a constantly re - equipping Condor Legion . In Operation " Rügen " , waves of planes bombed and strafed targets in Guernica leaving 1 , 685 people dead and over 900 injured . The offensive on Bilbao was supported by ground units and extensive air operations . It proved the worth of the Legion to the Nationalist cause . The Legion also took part in the Battle of Brunete and both land and air forces were involved in the Battle of Teruel . Up to 100 sorties a day were launched during the Nationalists ' counter - offensive . The continued Nationalist offensive on Aragon in April – June 1937 , including the Battle of Belchite , involved bombing raids and the use of the Legion ' s ground forces . On 24 – 25 July , Republican forces launched the Battle of the Ebro . Reconnaissance units of the Condor Legion warned Nationalists forces , but this went unheeded . 422 sorties by the Legion ' s aircraft had considerable effect . A reinforcement of the Legion enabled an important Nationalist counter - attack . On the sea , the Maritime Reconnaissance Staffel of the Condor Legion acted against Republican shipping , ports , coastal communications and occasionally inland targets . The German North Sea Group around Spain , part of the Kriegsmarine , consisted of the pocket battleships " Deutschland " and " " Admiral Scheer " , the light cruiser " Köln " , and four torpedo boat s . In addition , Operation Ursula saw a group of German U - boat s active around Spain , but was ultimately a failure . Motivation and volunteers . In the years following the Spanish Civil War , Hitler gave several possible motives for German involvement . Among these were the distraction it provided from German re - militarisation ; the prevention of the spread of communism to Western Europe ; the creation of a state friendly to Germany to disrupt Britain and France ; and the possibilities for economic expansion . Although the offensive on Madrid was abandoned in March 1937 , a series of attacks on weaker Republican - controlled areas was supported by Germany ; despite prolonging the Civil War , it would help to distract the other western powers from Hitler ' s ambitions in central Europe . The offensive on Vizcaya , a mining and industrial centre , would help fuel German industry . On 27 June 1937 , Hitler ( in a speech at Wurzburg ) declared he supported Franco to gain control of Spanish ore . Discussions over German objectives for intervention occurred in January 1937 . Germany was keen to avoid prompting a Europe - wide war , which at the time they felt committing further resources to Spain would do . Contradictory views were held by German officials : Ernst von Weizsäcker suggested it was merely a matter of graceful withdrawal ; Hermann Göring stated that Germany would never recognise a " red Spain " . A joint Italian – German decision , that the last shipments would be made by the start of February , was agreed . German aid would therefore prevent a Nationalist defeat with a minimum of commitment . Involvement in the Spanish Civil War had drawn Mussolini closer to Hitler , helping to get Mussolini ' s agreement for Hitler ' s plans for union ( " Anschluss " ) with Austria . The authoritarian Catholic , anti - Nazi Vaterländische Front government of autonomous Austria had been successfully opposing the rise of Fascism , and following the assassination of Austria ' s authoritarian chancellor , Engelbert Dollfuss in 1934 , had already successfully invoked Italian military assistance in case of a German invasion . Hitler ' s need to prevent an Italian invasion was settled with the Rome - Berlin Axis , partway into the Spanish Civil War . Around 5 , 000 Germans and Austrians served with the International Brigades , some of whom were political refugee s . There were few volunteers for the Nationalist side ( from any country ) , by comparison . Non - Intervention Agreement . Non - intervention , and with it the Non - Intervention Agreement , had been proposed in a joint diplomatic initiative by the governments of France and the United Kingdom , in order to prevent the war from escalating into a major pan - European conflict . On 4 August 1936 , non - intervention was put to Nazi Germany by the French . The German position was that such a declaration was not needed , but discussions could be held on preventing the spread of the war to the rest of Europe , so long as the USSR was present . It was mentioned at that meeting that Germany was already supplying the Nationalists . On 9 August , the Germans informed the British that ' no war materials had been sent from Germany and none will ' , which was blatantly false . One German Junker was captured when it came down in Republican territory . Its release would be required before Germany signed the Non - Intervention Pact . There was a growing belief that countries would not abide by the agreement anyway . Admiral Erich Raeder urged the German government to either back the Nationalists more completely , and bring Europe to the brink of war , or abandon them . On the 24th , Germany signed . It was at this point that the Non - Intervention Committee was created to uphold the agreement , but the double - dealing of the USSR and Germany had already become apparent . Germany consistently broke the agreement they had signed . The Non - Intervention Committee was established to enforce the Non - Intervention Agreement . Germany was represented by Joachim von Ribbentrop ( with Otto Christian Archibald von Bismarck as deputy ) but left the running to the Italian Dino Grandi , although they found working with him difficult . It became clear the Non - Intervention Agreement was not preventing German aid to the Nationalists . On 18 November , the German government recognised the Nationalists as the true government of Spain . Germany met the request to ban volunteers on 7 January . Hitler himself authored the German declaration . German uneasiness about the scale , limitations and outcomes of intervention in Spain remained . German diplomats spoke as if their men in Spain were genuine volunteers . However , Britain , France , Germany , Italy and Russia continued to believe a European war was not in their best interests . Control plan . Observers were posted to Spanish ports and borders , and both Ribbentrop and Grandi were told by their governments to agree to the plan , significant shipments already having taken place . The cost of the scheme was put at £898 , 000 , Germany would pay 16 % . The German delegation appears to have hoped the control plan was effective . In May , the Committee noted an attack on the German pocket battleship " Deutschland " . Germany and Italy said they would withdraw from the Committee , and from the patrols , unless it could be guaranteed there would be no further attacks . Early June saw the return of Germany and Italy to the committee and patrols . It continued to be a crime in Germany to mention German operations . Following attacks ( attributed to Republicans by Germany , but denied ) on the German cruiser " Leipzig " on 15 and 18 June , Germany and Italy once again withdrew from patrols , but not from the Committee . Discussions about patrols remained complicated . Britain and France offered to replace Germany and Italy in patrols of their sections , but the latter powers believed these patrols would be too partial . Early intervention . Following the military coup in Spain at the start of the Spanish Civil War , the Spanish Second Republic turned to the Soviet Union and France for support , and the Nationalists requested the support of Hitler ' s Germany and fascist Italy . The first attempt to secure German aviation was made on 22 July , with a request for 10 transport aircraft . Franco contacted Hitler directly . German ministers were split on whether to support the Nationalists , and possibly become embroiled in a European war as a result . Ultimately Hitler decided to support the Nationalists on 25 or 26 July , but was still wary of provoking a Europe - wide war . The Reich Air Travel Ministry concluded that Nationalist forces would need at least 20 Ju 52 s , flown by Deutsche Lufthansa pilots , to carry the Army of Africa from Spanish Morocco to Spain . This mission became known as Operation " Magic Fire " ( ) . The joint Spanish - German Sociedad Hispano - Marroquí de Transportes ( HISMA ) " Spanish - Moroccan Transport Company " and an entirely German company , the Raw Materials and Good Purchasing Company ( , ROWAK ) were established . This involvement was kept covert , hidden from both foreign and economic ministries , and funded with three million Reichmarks . The organisation and recruitment of German volunteers was also kept secret ; by 27 July the call for pilots had been made in major German cities . The first contingent of 86 men left on 1 August in civilian clothes , unaware of where they were going . They were accompanied with six biplane fighters , anti - aircraft guns and about 100 tons of other supplies . They were placed at Tablada airfield near Seville , and accompanied by German air transport , they began the airlift of Franco ' s troops to Spain . Germany ' s involvement grew in September to encompass the Wehrmacht ' s other branches ; Operation Magic Fire was renamed " Operation Guido " in November . A wide belief was that the soldiers would train Spanish Nationalists , and not engage the Republicans . In August , 155 tons of bombs were transferred from Germany through Portugal . Other military aid was provided . The head of the Kriegsmarine initially refused to provide submarines , but this changed after 24 October , upon the signing of the Rome - Berlin Axis , when it became clear to Mussolini ' s Italy would do the same . The Kriegsmarine also provided various surface ships and coordinated the movement of German supplies to Spain . German U - Boat s were dispatched to Spanish waters under the codename " Ursula " . In the two weeks following 27 July , German transports moved nearly 2 , 500 troops of the Army of Africa to Spain ; 1 , 500 between 29 July and 5 August . Transport planes were moved to Spain from Germany via San Remo in Italy . German aircraft continued to provide cover for ship movements in the Strait of Gibraltar . There were fuel shortages , however , these eased as more fuel arrived from Germany . By 11 October , the mission ' s official end , 13 , 500 troops , 127 machine guns and 36 field gun s had been carried into Spain from Morocco . Over this period there was a movement from training and supply missions of overt combat . The operation leader , Alexander von Scheele , was replaced by Walter Warlimont , and was moved into Franco ' s headquarters to coordinate military and diplomatic efforts . In September , 86 tons of bombs , 40 Panzer PzKpfw I tanks and 122 personnel had been landed in Spain ; they were accompanied with 108 aircraft in the July – October period , split between aircraft for the Nationalist faction itself and planes for German volunteers in Spain . German air crews supported the Nationalist advance on Madrid , and the successful relief of the Siege of the Alcázar . Ultimately , this phase of the Siege of Madrid was unsuccessful . Soviet air support for the Republicans was growing , particularly through the supply of Polikarpov aircraft . Warlimont appealed to Nazi Germany to step up support . Some Nazi figures , including Göring , were opposed , but following German recognition of Franco ' s government on 30 September , German efforts in Spain were reorganised and expanded . The existing command structure was replaced with the Winterübung Rügen , and the military units already in Spain were formed into a new legion , which was briefly called the Iron Rations ( ) and the Iron Legion ( ) before Göring renamed it the Condor Legion ( ) . The first German chargé to Franco ' s government , General Wilhelm von Faupel , arrived in November , but was told not to interfere in military matters . By mid - November , 20 German shipments had arrived in Spain , carrying supplies like ammunition , aviation fuel , rifles , grenades , radio equipment and both civilian and military vehicles . Göring ( who controlled Rheinmetall - Borsig ) supplied arms to the Republicans ; shipped to Greece supposedly for their use , the arms were transferred by Bodosakis to ships supposedly sailing to Mexico . He was also supplying the Nationalists , who got the best and latest weapons while the Republicans got the oldest and least serviceable . This supply peaked in 1937 – 38 . Nationalists identified 18 vessels to Republican ports from 3 January 1937 and 11 May 1938 , and estimated that Goering received the equivalent of one pound sterling per rifle . An earlier shipment from Hamburg to Alicante on 1 October 1936 by the Welsh ship " Bramhill " had 19 , 000 rifles , 101 machine guns and more than 20 million cartridges for the CNT militia in Barcelona . Nazi Germany also helped the propaganda war with a gift of a Telefunken transmitter for the newly created national radio service . The Condor Legion . The Condor Legion , upon establishment , consisted of the Kampfgruppe 88 , with three squadrons of Ju 52 bombers and the Jagdgruppe 88 with three squadrons of Heinkel He 51 fighters , the reconnaissance Aufklärungsgruppe 88 ( supplemented by the Aufklärungsgruppe See 88 ) , an anti - aircraft group , the Flakbteilung 88 , and a signals group , the Nachrichtenabteilung 88 . Overall command was given to Hugo Sperrle , with Alexander Holle as chief of staff . Scheele was transferred to become a military attaché in Salamanca . Two armoured units under the command of Wilhelm Ritter von Thoma , with 106 Panzer I s , were also operational . The Nationalists were supported by German and Italian units and equipment during the Battle of Madrid . However , the military situation in Madrid remained poor for the Nationalists , and both German and Italian aircraft ( under Franco ' s direction ) began bombing raids on the city as a whole . The Germans were keen to observe the effects of civilian bombings and the deliberate burning of the city . Offensives involving German aircraft , as well as the bombings , were unsuccessful . Increasing Republican air superiority became apparent , particularly the strength of the Soviet Polikarpov I - 15 and I - 16 aircraft . Historian Hugh Thomas described their armaments as " primitive " . Faupel , in November – December , urged the creation of a single German unit of 15 , 000 – 30 , 000 , believing it would be enough to turn the tide of the war to the Nationalists . Hans - Heinrich Dieckhoff argued this would be insufficient , and that larger measures could provoke the wrath of the Spanish . Between late 1936 and early 1937 , new aircraft were sent to the Condor Legion . Older aircraft were passed onto the Nationalists . By the end of 1936 , 7 , 000 Germans were in Spain . The British estimated that between January 1937 and August 1938 , 320 , 000 rifles and 550 , 000 revolvers were transferred to the Nationalists from Germany . German forces also operated in the Battle of Jarama , which began with a Nationalist offensive on 6 February 1937 . It included German - supplied ground forces , including two batteries of machine guns , a tank division , and the Condor Legion ' s anti - aircraft guns . Bombing by both Republican and Nationalist aircraft helped ensure a stalemate . It showed up the inadequacy of the Legion ' s aircraft , faced with superior Soviet - made fighters . The Legion ' s efforts only partly mitigated what was a significant defeat for the Nationalists at the Battle of Guadalajara during March . A joint Italian - German general had been set up in January 1937 to advise Franco on war planning . The defeat of a significant Italian force and the growing Soviet superiority in tanks and aircraft led the Germans to support a plan to abandon the offensive on Madrid and instead concentrate a series of attacks on weaker Republican - controlled areas . While many countries believed motorised troops to have been proven less effective than first thought , it was the inadequacy of the Italians as a fighting force that dominated German thought . The Vizcaya Campaign . The isolated area of Vizcaya , a predominantly Basque part of northern Spain , was the most immediate target , in what was called the War in the North . It was largely a Nationalist and Italian offensive , but was supported by a consistently re - equipping Condor Legion . Sperrle remained in Salamanca ; Wolfram von Richthofen replaced Holle in January as deputy and in actual command . The Legion ' s air force initially attacked the towns of Ochandiano and Durango . Durango had no anti - aircraft defence , and only minor other defences . According to the Basques , 250 civilians died on 31 March , including the priest , nuns and congregation of a church ceremony . The Germans , with their air raids , were hated . The Basque ground forces were in full retreat towards Bilbao , through the town of Guernica , which was attacked on 26 April in one of the most controversial events of the Spanish Civil War . In Operation Rügen , waves of planes bombed and strafed targets in the town . The number of casualties is a matter of controversy , with between 200 to 300 people killed ; the number reported dead by the Basques was 1 , 654 dead and 889 wounded . Several explanations were put forward by the Nationalists , including blaming the attack on the Republicans , that the attack on the town had been a prolonged offensive . However , the nature of the operation itself makes this seem unlikely . The offensive on Bilbao , when it eventually came on 11 July , was supported by ground units of the Condor Legion , and extensive air operations . It proved the worth of the Condor Legion to the Nationalist cause . Further campaigns . The Condor Legion also took part in the Battle of Brunete . The Legion was sent from the north to reinforce the broken line . There were repeated raids on Spanish Republican Army armoured vehicles and later defensive positions by both bombers and fighters based at Salamanca . Spanish Republican Air Force aircraft were ineffective , despite Nationalist fears , compared with German aircraft . The Legion lost eight aircraft , but claimed 18 victories . German tactics were also improved with the experience of Brunete , particularly the " en masse " use of tanks by the Nationalists . The Nationalists returned to focus on the capture of northern Spain . German test aircraft , with the latest models , faced an outdated Basque section ( " Escuadrilla vasca " ) of the Spanish Republican Air Force . Heavy aerial bombardment from 200 Nationalist , German and Italian planes was used far behind Basque lines in August 1937 , leading to the fall of Santander after the Battle of Santander on 1 September . The formal battle in Asturias ended with the fall of Gijón on 21 October . Germany immediately began to ship the products of the region ' s industry back to Germany . Sperrle argued repeatedly with Faupel , and against HISMA ' s monopoly . Faupel was replaced with Eberhard von Stohrer by Franco , through Sperrle . Sperrle also returned to Germany and was replaced by Helmuth Volkmann ; following disagreements with Volkmann , Von Richthofen would be replaced with Hermann Plocher in early 1938 . The Condor Legion began a week of strikes against Republican airfields , halted by the Republican advance on Teruel and the ensuing Battle of Teruel . Both the Legion ' s land and air forces were used . Poor weather resulted in few flights , and the town fell to Republican forces on 6 January . Up to 100 sorties a day were launched during the Nationalist ' s counter - offensive through the Alfambra valley . Teruel was retaken on 22 February . The continued Nationalist offensive on Aragon in April – June 1937 , including the Battle of Belchite , involved bombing raids and the use of the Legion ' s ground forces . The Legion was switched to focus in the north , towards the Segre river , before moving south again following Nationalist successes . Hitler ' s words to his colleagues belied a change in attitude about the war in Germany – that a quick victory in the war was not desirable , a mere continuation of the war would be preferable . German policy would be to prevent a Republican defeat . However , casualties were beginning to mount for the Legion and , combined with a resurgence in Republican air activity , the Nationalist advance stalled . Arguments over the bill to the Germans – now rising at 10 million Reichmarks a month – continued , unresolved . The Legion ' s materiel had been exhausted . On 24 – 25 July , Republican forces launched the last major offensive of the war , the Battle of the Ebro . Reconnaissance units of the Condor Legion had noticed a troop build - up , and warned Nationalists forces . The warning went unheeded . Although the Republic gained ground , Republican forces failed to gain control of Gandesa , with 422 sorties by the Legion having considerable effect . However , tensions in Czechoslovakia and a shortage of pilots in Germany led to the return of 250 pilots from the Legion . Although trained Spaniards made up some of the shortfall , Volkmann complained to central command in Berlin , which led to his recall in September . During the battle , which saw 113 days of fighting , only 10 aircraft were lost ( some by accident ) ; the Legion claimed around 100 Republican aircraft . Only five aircrew had been killed , and six captured . Aid from Germany temporarily halted in mid - September . Germany and Nationalist Spain settled the issue of German interests in Spanish mines . The Legion took a short break from active duty to receive new aircraft , including Bf 109Es , He 111Es and Js , and Hs 126As , bringing its strength to 96 aircraft , around a fifth of the Nationalist ' s force as a whole . Von Richthofen returned to Spain in overall command , with Hans Seidemann as chief of staff . This reinforcement may have been the single most important intervention by a foreign side in the war , enabling a counterattack after the Battle of the Ebro . It mainly took part in operations against the remaining Republican air force during January – February 1939 , with considerable success . It was rapidly dissolved . The men returned on 26 May ; the best aircraft were returned to Germany and the rest of the equipment bought by the new Spanish regime . The Condor Legion claimed to have destroyed 320 Republican planes using aircraft ( either shot down or bombed on the ground ) , and shot down another 52 using anti - aircraft guns . They also claimed to have destroyed 60 ships . They lost 72 aircraft due to hostile action , and another 160 to accidents . Maritime operations . Condor Legion . The Maritime Reconnaissance Staffel 88 ( ) was the Condor Legion ' s maritime unit under the command of Karl Heinz Wolff . Operating independently of the land - based division , it acted against Republican shipping , ports , coastal communications and occasionally inland targets such as bridges . It used floatplane s , starting with the Heinkel He 60 , which began operating in October 1936 . Beginning in June , operations were expanded to allow attacks on all Republican ports , so long as no British ships were present . Ten ships were attacked in the second half of 1937 ; however , the Norwegian torpedoes being used proved ineffective , and strafing or bombing targets was used instead . The arrival of Martin Harlinghausen saw operations expand , targeting Alicante , Almeria , Barcelona and Cartegena . As naval activity declined , inland targets became more numerous , and night missions began . Activities in support of ground forces became the main focus of the unit until the end of hostilities . In total , eleven men were killed in action , and five others died due to accident or illness . Kriegsmarine . Overtly , the Kriegsmarine was part of the force enforcing the non - intervention agreement signed on 28 September 1936 , which barred its signatory countries from interfering in the Civil War . However , this agreement was clearly broken by France , the USSR , Germany and Italy , who supported one faction or another . As a result , the German pocket battleship s " Deutschland " and " " Admiral Scheer " stood guard in the Strait of Gibraltar to prevent interference from Republican ships while Franco transported his troops to the Spanish mainland . By mid - October , the German North Sea Group around Spain consisted of the pocket battleships " Deutschland " and " Admiral Scheer " , the light cruiser " Köln " , and four torpedo boat s . They quickly uncovered evidence that the Soviet Union was supplying the Republicans . They also helped the aircraft bound for the Condor Legion to cross the Mediterranean and assisted in the Battle of Málaga . On 29 May , the " Deutschland " was attacked by two Republican planes . It was claimed that their Soviet pilots had mistaken it for the Nationalist ship " Canarias " , or else had been fired upon by it . 32 sailors were killed , the Kriegsmarine ' s greatest loss of life in the war . After a retaliatory attack on Almeria ( Valencia had been the original target , but minefields posed too great a problem ) , Germany came close to withdrawing from the agreement , but British diplomatic efforts to keep Germany patrolling prevailed . After the Germans claimed that " Leipzig " had been attacked by an unidentified submarine off Oran , it formally withdrew from international patrols to enforce the agreement . Republican minister of defense Indalecio Prieto considered a declaration of war on Germany , but Soviet fear of a world war prevented this . Operation Ursula . Operation Ursula ( named after the daughter of Karl Dönitz ) saw a group of German U - boat s active around the waters near Spain against the Spanish Republican Navy , under the overall command of Hermann Boehm ( Konteradmiral since 1934 , and Vizeadmiral since April 1 , 1937 ) in Berlin . It began on 20 November 1936 , with the movement of the " U - 33 " and " U - 34 " from Wilhelmshaven . Any identification marks were obscured , and the whole mission was kept secret . They entered the Mediterranean on the night of 27 – 28 November , taking over from Italian submarine patrols . If damaged , they were to sail to La Maddelena , and enter under an Italian ensign . " U - 33 " operated around Alicante , and " U - 34 " around Cartagena . Difficulties in identifying legitimate targets and concerns about discovery limited their operations . The torpedoes they used also often malfunctioned . During their return to Wilhelmshaven in December , the Spanish Republican submarine " C - 3 " was sunk ; the Germans claimed this was due to a torpedo fired from " U - 34 " , although the Republicans ' enquiry claimed its loss was due to an internal explosion . Their return marked the official end of Operation Ursula . However , it does seem that further submarines were sent in mid - 1937 , but details of the operation are not known ; six ( " U - 25 " , " U - 26 " , " U - 27 " , " U - 28 " , " U - 31 " and " U - 35 " ) are believed to have been involved . Five submarine commanders received the Spanish Cross in Bronze without Swords in 1939 . Outcome . Early intervention helped to ensure that the Nationalist faction survived the initial stages of the war ; German involvement then steadily expanded . The training they provided to Nationalist force proved as valuable , if not more so , than direct actions . Approximately 56 , 000 Nationalist soldiers were trained by various German detachments in Spain , who were technically proficient ; these covered infantry , tanks and anti - tank units , air and anti - aircraft forces , and those trained in naval warfare . The Condor Legion spearheaded many Nationalist victories , particularly providing air dominance from 1937 onwards ; 300 air - to - air victories were claimed , although this was dwarfed by some 900 claimed by Italian forces . Spain provided a proving ground for German tank tactics , as well as aircraft tactics , the latter being only moderately successful . Ultimately , the air superiority which allowed certain parts of the Legion to excel would not be replicated in World War II because of the unsuccessful Battle of Britain . A total of approximately 16 , 000 German citizens fought in the Civil War , mostly as pilots , ground crew , artillery men , tank crew , and as military advisers and instructors . About 10 , 000 Germans was the maximum strength at any one time . Approximately 300 Germans were killed . During the course of the war , Germany sent 732 combat aircraft and 110 trainer aircraft to Spain . German aid to the Nationalists amounted to approximately £43 , 000 , 000 ( $ 215 , 000 , 000 ) in 1939 prices . This was broken down in expenditure to : 15 . 5 % used for salaries and expenses , 21 . 9 % used for direct delivery of supplies to Spain , and 62 . 6 % expended on the Condor Legion . No detailed list of German supplies furnished to Spain has been found . Franco had also agreed to sign over the output of six mines to help pay for German aid .