On July 26, 1953, he led approximately 160 men in a suicide attack on the Moncada military barracks in Santiago de Cuba in hopes of sparking a popular uprising. Fidel was arrested and most of the men were killed. After a trial in which he defended himself sloppily, the government sentenced him to 15 years in prison. He and his brother Raúl were finally released in 1955 as part of a political amnesty with the Batista government. The two brothers then went to Mexico to lead their campaign against the Batista regime. It was in Mexico that Fidel began organizing Cuban exiles into a revolutionary group called July 26.