During World War I, Péret enlisted in the French army's Cuirassiers, to avoid being jailed for defacing a local statue with paint.

During a routine movement of his unit via train, he discovered a copy of Pierre Albert-Birot's avant-garde magazine SIC: Sons Idées Couleurs, Formes, founded in January 1916, sitting upon a bench on the station platform.

[5] After returning to France, he went to Spain at the outbreak of the Spanish Civil War and entered into an anarchist militia at Pino de Ebro.

Upon his release, he sailed for Mexico with the aid of the American-based Emergency Rescue Committee to study pre-Columbian myths and American folklore.

In Mexico City he became involved with the European intellectual community around the Austrian painter and surrealist Wolfgang Paalen living there in exile.