Aragon Offensive The Aragon Offensive was a Nationalist campaign during the Spanish Civil War , which began after the Battle of Teruel . The offensive , which ran from March 7 , 1938 to April 19 , 1938 , smashed the Republican forces , overran Aragon , and conquered parts of Catalonia and the Levante . Introduction . The Battle of Teruel exhausted the material resources of the Republican Army , and wore out the veteran Republican troops . A slowdown of supplies from the Soviet Union exacerbated the difficulties of the Republican government , whose armament industry in Catalonia was already beleaguered . At the same time , however , Francisco Franco had concentrated the bulk of the Nationalist forces in the east and was preparing to drive through Aragon and into Catalonia and the Levante . The Nationalists were able to concentrate 100 , 000 men between Zaragoza and Teruel with the best troops in the lead . Even though the Nationalist Army was numerically inferior to the Republican forces , the Nationalists were better equipped and had almost 950 airplanes , 200 tanks and thousands of trucks . In addition to his foreign aid from Nazi Germany and Fascist Italy , Franco by this stage had the advantage of controlling the efficiently - run industries in the Basque Country . Nationalist army . The attacking army was commanded by Fidel Dávila Arrondo , with Juan Vigón Suerodíaz as his second in command . José Solchaga , José Moscardó , Antonio Aranda , and Juan Yagüe would command army corps alongside the Italian General Berti . A reserve commanded by García Escámez and García Valińo constituted the main force . José Enrique Varela with the Army of Castile was to stand by , on the wings of the attack , at Teruel . The Condor Legion was also on standby . Colonel Ritter Von Thoma , its commander , convinced Franco to concentrate his tanks rather than spread them out . Republican army . Because of the material losses at the Battle of Teruel , half the Republican troops even lacked rifles , and since the best troops had been withdrawn to refit , the frontline defenders had no combat experience . The Republic could not replace its lost equipment as Soviet aid was starting to dry up . Essentially , the Republican army was surprised by the Nationalist attack . The Nationalists had redeployed their forces much faster than the Republican general staff thought possible . Although warned by spies , the Republican generals were convinced that the Nationalists would resume the Guadalajara offensive . Another error made by the Republican military leadership was assuming that the Nationalists were as tired and worn out as the Republicans . Attack begins . The Nationalist attack began on March 7 , 1938 , preceded by a heavy artillery and aerial bombardment . At 6 : 30 a . m . , three Nationalist armies attacked the Republican line stretched between the Ebro River and Vivel del Rio . The northern part of the attack was carried out by Yagüe ' s elite Army of Africa , supported by the Condor Legion and forty - seven artillery batteries . The Nationalists broke the front in several places on the first day of the battle . Yagüe advanced down the right bank of the Ebro , slashing through all defences . Solchaga won back Belchite on March 10 , XV International Brigade , with its US , Canadian and British complement , being the last unit out of that destroyed town . The commander of the Abraham Lincoln Battalion , part of the XV International Brigade , Robert Merriman , was killed during the retreat . The Italians attacked at Rudilla , met some initial resistance and then , led by the Black Arrows ( Flechas Negras Division ) broke through . Everywhere the Republican forces were falling back . Many , soldiers and officers , just ran , and the retreat became a rout . In addition , the spreading anti - Communist sentiment in the Republican Army deepened the demoralization . The Communist commanders were accusing each other of various acts of wrongdoing or failure to act . André Marty and Enrique Líster attacked each other . Lister started a policy of shooting commanders of retreating troops . This created discussion among the Communists since Lister was a Communist and the commanders being shot were also Communists . Republican disaster . Even as Rojo ordered the Republican concentration at Caspe , the Italians were approaching Alcañiz , and the Republican rout became absolute . Even where a Republican unit would fight effectively , it had to fall back because of the collapse of neighboring units . Entire units fell apart and desertions became rife . The Italian and German airplanes controlled the skies ; their bombers attacked the fleeing Republican units with aerial protection from modern fighters . Karol Świerczewski , known as General Walter , commander of the International Brigades , barely escaped capture at the fall of Alcañiz . Finally , after two days of heavy fighting , Caspe fell on March 17 to Varela ' s attacking army . The International Brigade performed valiantly in the defense , but was driven off . After eight days , the Nationalists were seventy miles east of the positions they had held when the battle started . This first part of the offensive punched a huge hole in the front , created a salient from Belchite to Caspe to Alcañiz and back to Montalbán . The Nationalist Army now paused before the Ebro and Guadalupe Rivers to reorganize . But on March 22 , the attack started again , this time in the area east of Zaragoza and Huesca . This part of the front that the Republic had held since August 1936 , was lost in one day . The villages in eastern Aragon that had experienced social revolution , either by their own actions or from the anarchist columns from Catalonia , were all taken by the Nationalists , with many of the inhabitants becoming refugees . In this part of the offensive , Barbastro , Bujaraloz and Sariñena succumbed to the Nationalists . On March 25 , Yagüe took Fraga and entered Catalonia . He attacked the next town , Lleida , but El Campesino held him off for a week , giving the Republicans a chance to withdraw with valuable equipment . The retreat of the Republican forces was covered by Colonel Duran ' s Mountain Group in the Maestrazgo , the high plains of southern Aragon . In the north , Republican forces pinned Solchaga down in the Pyrenees , but in the south , the Nationalists drove across the Maestrazgo . Almost everywhere , the Republicans started to fall apart . The various factions started to accuse each other of treachery . The Communists starved anarchist troops of needed munitions . André Marty , the overall commander of the International Brigades , travelled around looking for traitors , but he could not prevent the virtual destruction of the International Brigades . Republican troops suffered arbitrary executions with officers sometimes being shot in front of their men . In general , the campaign seemed lost , and nobody knew where the rout would end . End of the campaign . The campaign was decided by air power . The plains of Aragon provided easy landing fields allowing rapid air support from close behind the front . Nationalist aircraft continually drove back the Republicans , forcing them to abandon position after position and attacked the retreating columns . Both Germans and Soviets learned valuable lessons about the use of fighters in support of infantry . On the ground , Lleida and Gandesa fell on April . One hundred and forty American and British soldiers from the XV International Brigade became prisoners of the Nationalists . Also on this day , Aranda ' s troops saw the sea for the first time . In the north , the Nationalist advance continued and by April 8 , Barcelona ' s hydro - electric plants in the Pyrenees fell to the surging Nationalists . Barcelona ' s industries suffered a severe decline , and the old steam plants were restarted . The Nationalists could easily have taken Catalonia and Barcelona , but Franco made a decision to advance to the coast . This decision turned out to be a strategic mistake , but his intelligence reports suggested that to extend the conflict further into Catalonia might draw French intervention . He directed that the attack continue towards the sea . By April 15 the Nationalists had reached the Mediterranean sea at Vinaroz and by April 19 , the Nationalists held forty miles of the Mediterranean coastline . This series of victories that started with Teruel inspired great confidence in the Nationalists that the war was almost won . In the meantime , the French had reopened the border , and military aid that had been purchased and piling up in France because of the embargo , streamed into Spain and to the Republican forces . This slowed the Nationalists and the Republican defense stiffened . The disaster was contained for the time being , and although the Nationalists pursued other attacks in the north toward the Segre River and in the Valencia area , the Aragon Offensive was for all intents and purposes concluded by April 19 . The Nationalist attack was spent and the resistance on the coast was much more formidable .