During the First Sudanese Civil War, Tanginye joined the Anyanya movement. Tanginye disliked the Addis Ababa Agreement that ended the civil war in 1972, so he joined the mainly Nuer Anyanya II. In 1984, he and other Anyanya II leaders allied with the Sudanese government in order to fight the mainly Dinka Sudan People's Liberation Army. While large numbers of the Anyanya II joined the SPLA around 1988, Tanginye and his forces stayed allied to the government. Tanginye and his forces joined the SPLA-Nasir faction after it split from the SPLA in 1991. Tanginye became a part of the South Sudan Defence Forces as part of the Khartoum Peace Agreement of 1997. After the defection of Lam Akol in October 2003, the Sudanese government feared losing the Upper Nile area. They provided Tanginye's forces with boats, trucks, guns, and ammunition, which Tanginye used in a campaign in the modern Western Nile State in 2004 designed to rid the area of SPLA support. The campaign killed hundreds and displaced tens of thousands of civilians through its use of burning and looting villages. Tanginye was made a major general of the Sudanese Armed Forces in 2004. Unlike many of the pro-Sudan militiamen who were integrated into the SPLA, Tanginye did not sign the Juba Declaration of 8 January 2006. However, Brig. John Both did integrate into the SPLA and took about 70 percent of Tanginye's force with him, leaving the remaining forces estimated at less than 500.