In 1952, Fidel Castro, a young lawyer running for a seat in the Chamber of Representatives for the Partido Ortodoxo, founded in 1947 to oppose government corruption and reform, circulated a petition to depose Batista's government on the grounds that it had illegitimately suspended the electoral process. However, the courts did not act on the petition and ignored Castro's legal challenges. Castro thus resolved to use armed force to overthrow Batista; he and his brother Raúl gathered supporters, and on 26 July 1953 led an attack on the Moncada Barracks near Santiago de Cuba. The attack ended in failurethe authorities killed several of the insurgents, captured Castro himself, tried him and sentenced him to 15 years in prison. However, the Batista government released him in 1955, when amnesty was given to many political prisoners, including the ones that assaulted the Moncada barracks. Castro and his brother subsequently went into exile in Mexico, where they met the Argentine revolutionary Ernesto "Che" Guevara. While in Mexico, Guevara and the Castros organized the 26 July Movement with the goal of overthrowing Batista. In December 1956, Fidel Castro led a group of 82 fighters to Cuba aboard the yacht "Granma", landing in the eastern part of the island. Despite a pre-landing rising in Santiago by Frank País Pesqueira and his followers among the urban pro-Castro movement, Batista's forces promptly killed, dispersed or captured most of Castro's men.