He led campaigns against rebels in the southern Sudan in the 1950s and joined in leftist attempts to overthrow the civilian government. Following a coup, he became Prime Minister in 1969 and Chairman of the Revolutionary Command Council. President from 1971 to 1985, in 1972 he ended the civil war in the southern Sudan, granting it local autonomy. He switched from socialist economic policies to capitalism, to make the Sudan a major food producer. A devout Muslim, he proposed a new Islamic Constitution in December 1984 that made Islamic law apply to everyone. This was opposed in southern Sudan, where the majority of the population were not Muslim, and a military coup overthrew him in 1985. He returned to Sudan in 1999 and stood unsuccessfully in the 2000 presidential elections.