In response to the growing unity and strength of the Congress Movement as a united front following the adoption of the Freedom Charter, the government arrested 156 political leaders in a mass police swoop on 5 December 1956 and charged them with high treason, a grave charge carrying the death penalty. They were accused of participating in a treasonable conspiracy, inspired by international Communism, to overthrow the South African State by violent means. The trial dragged on for four years, with the last accused being acquitted in 1961.