In the late 1960s, I joined the Anyanya in the First Sudanese Civil War. By the time of the 1972 Addis Ababa Agreement, I was a low-ranking officer. In 1983, when John Garang joined an army mutiny I had been sent to put down, me and other Southern leaders joined the rebel Sudan People's Liberation Movement (SPLM) in the second civil war. Garang had little military field experience and relied upon the more experienced Anyanya veterans, including myself, to actually carry out the ground war. I eventually rose to head the SPLA's military wing.

An attempt to remove me from my post as SPLA chief of staff in 2004 nearly caused the organization to split. Following the signing of the Comprehensive Peace Agreement formally ending the war in January 2005, which I had helped start, I was appointed Vice President of Southern Sudan. Perhaps significantly, former Southern Sudan president John Garang like myself is of the Dinka people, though of a different clan. After the death of Garang in a helicopter crash of 30 July 2005, I was chosen to succeed to the post of First Vice President of Sudan and President of Southern Sudan. I'm popular among the military wing of the SPLM for my battlefield victories and among the populace for my unambiguous pro-secession stance.

My comments in October 2009 that the forthcoming independence referendum was a choice between being "a second class in your own country" or "a free person in your independent state" were expected to further strain political tensions. Reports in January 2010 that I would not contest April elections for Sudanese president, but would focus on re-election as president of Southern Sudan were interpreted to mean that the SPLM priority is independence.

I was re-elected with 93% of the vote in the 2010 Sudanese election. Although the vote on both the national and sub-national level was criticized by democratic activists and international observers, the overwhelming margin of my re-election was noted by some media as being "Step One" in the process of secession. Following my re-election, Omar al-Bashir reappointed me as the First Vice President of Sudan in accordance with the interim constitution.