in government required a change in the co-dominium agreement. Neither Britain nor Egypt would agree to a modification. Moreover, the British regarded their role as the protection of the Sudanese from Egyptian domination. The nationalists feared that the eventual result of friction between the co-dominium powers might be the attachment of northern Sudan to Egypt and southern Sudan to Uganda and Kenya. Although they settled most of their differences in the 1936 Treaty of Alliance, which set a timetable for the end of British military occupation, Britain and Egypt failed to agree on Sudan's future status. Nationalists and religious leaders were divided on the issue of whether Sudan should apply for independence or for union with Egypt. The Mahdi's son, Abd ar Rahman al Mahdi, emerged as a spokesman for independence in opposition to Ali al Mirghani, the Khatmiyyah leader, who favored union with Egypt. Coalitions supported by each of these leaders formed rival wings of the nationalist movement. Later, radical nationalists and the Khatmiyyah created the Ashigga, later renamed the National Unionist Party (NUP), to advance the cause of Sudanese-Egyptian unification. The moderates favored Sudanese independence in cooperation with Britain and together with the Ansar established the Umma Party. The road to independence As World War II approached, the Sudan Defence Force assumed the mission of guarding the Sudanese frontier with Italian East Africa (present-day Ethiopia and Eritrea). During the summer of 1940, in what became the first moves of the East African Campaign, Italian forces invaded the Sudan at several points and captured the railway junction at Kassala and other villages along the border. However, while Port Sudan was raided by irregular Eritrean forces in August 1940, the SDF prevented an Italian advance on the Red Sea port city. In January 1941, the SDF, expanded to about 20,000 troops, retook Kassala and participated in the Empire offensive that routed the Italians in Eritrea and liberated Ethiopia by the end of the year. Some Sudanese units later contributed to the Eighth Army's successful North African Campaign. In the immediate postwar years, the co-dominium government made a number of significant changes. In 1942 the Graduates' General Conference, a quasi-nationalist movement formed by educated Sudanese, presented the government with a memorandum that demanded a pledge of self-determination after the war to be preceded by abolition of the "closed door" ordinances, an end to the separate curriculum in southern schools, and an