Under the terms of the 1972 peace settlement, most of the Anya Nya fighters were absorbed into the national army, although a number of units unhappy with the agreement defected and went into the bush or took refuge in Ethiopia. Angry over Sudan's support for Eritrean dissidents, Ethiopia began to provide help to Sudan's independent rebel bands. The rebel forces gathered more recruits among the Dinka and Nuer people, the largest groups in the south, and eventually adopted the name of Anya Nya II.

Those original Anya Nya who had been absorbed into the army after the 1972 peace accord were called upon to keep the guerrillas in check and at first fought vigorously on behalf of the national government. But when in 1983 Nimeiri adopted policies of redividing the south and imposing Islamic law, the loyalty of southern soldiers began to waver. Uncertain of their dependability, Nimeiri introduced more northern troops into the south and attempted to transfer the ex-guerrillas to the north. In February 1983, army units in Bor, Pibor Post, and Pochala mutinied. Desertions and mutinies in other southern garrisons soon followed.

In mid-1983 representatives of Anya Nya II and of the mutinous army units meeting in Ethiopia formed the Sudanese People's Liberation Army (SPLA). John Garang, a Dinka Sudanese, was named its commander and also head of the political wing, the Sudanese People's Liberation Movement (SPLM). The southern forces in rebellion failed to achieve full unity under Garang, and, in a struggle for power, the dissident units composed of elements of Anya Nya II were routed by Garang's forces. The defeated remnants, still calling themselves Anya Nya II, began to cooperate with the national army against the SPLA.

Still scarcely an effective fighting force, the SPLA relied at first on ambushes of military vehicles and assaults on police stations and small army posts, mainly in the Nuer and Dinka areas of Aali an Nil Province and northern and eastern Bahr al Ghazal Province. An SPLA attempt to invade eastern Al Istiwai in early 1985 was met with stiff resistance by the army and government militias. But by 1986 the SPLA was strong enough to hold the important town of Rumbek in southern Bahr al Ghazal for several months and was also able to press an attack against Waw, the provincial capital. During 1987, the SPLA took Pibor Post and Tonga in Aali an Nil, and by the beginning of 1988, it had captured a number of towns on the Ethiopian border and near the White Nile. Advancing northward into Al Awsat Province, it held Kurmuk and Qaysan for a time in late 1987.

The SPLA was opposed by many communities in Al Istiwai Province where the Dinka and Nuer were not popular. The national army was assisted by a militia of the Mundari people, but the SPLA was gradually able to consolidate its position in eastern Al Istiwai. By 1988 the SPLA controlled the countryside around Juba, the major southern city, besieging at least 10,000 government troops, who were virtually cut off from supplies except for what could be delivered by air. During a general offensive in early 1989, the SPd23 SPLA captured Torit and other strategic towns of eastern Al Istiwai. From May to October 1989, an informal truce prevailed. After the conflict resumed, the areas being contested were principally in western and central Al Istiwai, focusing on the government garrisons at Juba and Yei (see fig. 8). The fighting often consisted of ambushes by the more lightly armed but mobile guerrillas against government convoys moving supplies from the north. With captured weapons and arms imported from Ethiopia and other African countries, the SPLA was increasingly capable of conducting orthodox warfare employing artillery and even armored vehicles, although its forces still avoided conventional engagements against government units.

Figure 8. The Civil War in Southern Sudan, Spring 1991

Anya Nya II began to crumble in 1987, many units and their commanders deserting to the SPLA. But since 1985, the government had been encouraging the formation of militia forces in areas where opposition to the Dinka- and Nuer-dominated SPLA was strongest. These militias were soon playing a major role in the fighting and were partly responsible for the ravages that the civilian population has been forced to endure. The arming of tribal groups inflamed existing intercommunal conflicts and resulted in the deliberate killing of tens of thousands of noncombatants and a vast displacement of civilians.

Millions of villagers were forced from their homes as a consequence of the fighting and the depredations of militias, the SPLA, and Anya Nya II. Devastation of northern Bahr al Ghazal by the roving murahalin (Arab militias) forced large numbers of destitute people to evacuate the war zone in 1986 and 1987, many of them making their way to northern Sudan to escape starvation. Raiding decreased in 1988 and diminished further in 1989 as a result of depopulation of the land and a stronger SPLA presence in northern Bahr al Ghazal. Nevertheless, the migrations continued because of the severe food shortage. Almost 1 million southerners were believed to have reached Khartoum in 1989, and hundreds of thousands had appeared in other towns and cities. About 350,000 Sudanese refugees were registered in Ethiopia in 1989, at least 100,000 were in Juba, and 28,000 crossed into Uganda to escape the fighting in southern Al Istiwai.

Data as of June 1991