Giù la testa (1971)

In "Giu la testa", an Irish explosives expert named John (James Coburn) joins forces with Mexican thug Juan (Rod Steiger) to plan a bank heist in a get-rich-quick-and-easy scheme during the uprising against Mexico's dictator Díaz. But when they break into the bank, they are dumbfounded to discover that it's not really a bank at all; they've forced their way into a converted prison. The captives tell John and Juan that they are political prisoners, victims of the Mexican Revolution. Juan is extremely angry at their bank robbery failure, but John sympathizes with the prisoners of war. John has flashbacks to his own time fighting the guerrilla campaign supporting the Irish Republic. So John decides to put his skills with explosives to work and help the revolutionaries. Juan is less than thrilled with the idea at first, but slowly he begins to appreciate an ardent friendship with his companion and he helps in the cause too.