Volunteers from many countries fought in Spain, most of them on the Republican side. About 32,000  men and women fought in the International Brigades including the American Lincoln Battalion and Canadian Mackenzie–Papineau Battalion, organized in close conjunction with the Comintern to aid the Spanish Republicans. Perhaps another 3,000  fought as members of the Confederación Nacional del Trabajo (CNT) and the Workers’ Party of Marxist Unification (POUM) militias. Those fighting with POUM most famously included George Orwell and the small ILP Contingent. While not supported officially, many American volunteers such as the Abraham Lincoln Brigade fought for the Republicans.
‘Spain’ became the cause célèbre for the left-leaning intelligentsia across the Western world, and many prominent artists and writers entered the Republic’s service. As well, it attracted a large number of foreign left-wing working class men, for whom the war offered not only idealistic adventure but also an escape from post-Depression unemployment. Among the more famous foreigners participating on the Republic’s side was George Orwell, who went on to write about his experiences in Homage to Catalonia. Orwell’s novel Animal Farm was loosely inspired by his experiences and those of other members of POUM at the hands of Stalinists when the Popular Front began to fight within itself, as were the torture scenes in Nineteen Eighty-Four. Ernest Hemingway‘s novel For Whom the Bell Tolls was inspired by his experiences in Spain. George Seldes reported on the war for the New York Post. The third part of Laurie Lee‘s autobiographical trilogy, A Moment of War, is also based on his Civil War experiences. Norman Bethune used the opportunity to develop the special skills of battlefield medicine. As a casual visitor, Errol Flynn used a fake report of his death at the battlefront to promote his movies. In the Philippines, a pro-Republican magazine named Democracia had writers including anti-fascist Spaniards and Filipino-Spaniards as well as Filipino progressives like Pedro Abad Santos, chairman of the Socialist Party, and Bishop Gregorio Aglipay of the Philippine Independent Church.
Probably 32,000 foreigners fought in the International Brigades (which probably never exceeded 20,000 at any one time <Citation needed>). An estimated 3,000 volunteers fought in other Republican forces during the conflict. Additionally, about 10,000 foreigners participated in medical, nursing, and engineering capacities.
The International Brigades included 9,000 Frenchmen, of whom 1,000 were killed; 5,000 Germans and Austrians of whom 2,000 died, and also about 3,000 from Poland at the time. The next highest number was from Italy with 3,350 men. Then came the United States (2,800 men with 900 killed) and the United Kingdom (2,000 with 500 killed). There were also 1,500 Czechs; 1,500 Yugoslavs; 1,500 Canadians; 1,000 Hungarians and 1,000 Scandinavians, about half of whom were Swedes. The rest came from a “claimed” 53 countries. 800 Swiss volunteered, 300 of whom would be killed. 90 Mexicans also participated. It has been estimated that between 3,000 to 10,000 of the volunteers were Jewish. About 200 volunteers were from Palestine (of Jewish and Arab origin).
Approximately one third of Irishmen who fought for Republicans died, a group composed primarily of socialists, trade unionists, and former IRA members. The “Connolly Column” of the International Brigades was named after the Irish socialist leader executed after 1916 Easter Rising, James Connolly.
Patriotism invoked to oppose the invader
Patriotism was invoked by both sides and the struggle presented as one of the Spanish people against the foreign invasion.
The instrumental use of nationalism on the republican side came from the communists. The heroic Spanish people were to rise against foreign invasion directed by traitors belonging to the upper classes, the clergy and the army, now at the service of the ‘fascist-imperialist world coalition’. The true Spain was represented by the lower classes; – outside the nation in arms were bourgeois traitors, the fascists, the clergymen, and false revolutionaries (dissident communists, radical anarchists, etc.) ‘serving fascism’. With the exception of the anti-Stalinist communists of the POUM, nationalist rhetoric developed by the PCE soon extended to other left-wing and republican literature. Republican propaganda made use of pre-existing icons depicting foreigners in certain ways. The Italians were presented as effeminate, cowardly and presumptuous, the Germans as arrogant. The Foreign Legionnaires were an international mob of criminals and thieves. Cartoons in the republican press often depicted the rebel army as a multinational gang of foreign mercenaries. The presence of Moorish troops was exploited from the outbreak of the conflict and Moorish troops presented as black-faced, barefoot, hungry, and eager to steal and kill. “The Moors were supposedly wild and cowardly, uncivilized and anxious to rape white women. Only a few appeals during the first months of the war were aimed at convincing the ‘Moorish proletarian brother’ to desert.”
Spanish nationalist sentiment was used by the rebels to present the struggle as one for the patria and its Catholic essence which was supposed to be under the threat of becoming a ‘Russian colony’, the fault of traitors and ‘international agents’. ‘Anti-Spain’ was embodied by liberalism, atheism, freemasonry, international Jewry and regional separatism. The communist invader was a dehumanised foreigner – the ‘wolves of the Russian Steppes‘. A legionnaire officer emphasised that the war was one ‘of Spaniards against Russians!’ Francoist propaganda presented the enemy as an invading army, or as the puppet of foreign powers. The involvement of Moorish troops in a Catholic crusade was explained as that of defenders of religion in the face of the godless, the anti-clerical, the anti-Islamic, and a common religious rival (the Jews) – and they were forced to ignore the previous Moroccan war propaganda