In January 1899, an Anglo-Egyptian agreement restored Egyptian rule in Sudan but as part of a condominium, or joint authority, exercised by the United Kingdom and Egypt.
Although it emphasized Egypt's indebtedness to Britain for its participation in the reconquest, the agreement failed to clarify the juridical relationship between the two condominium powers in Sudan or to provide a legal basis for continued British governing of the territory on behalf of the Khedive.
When World War I broke out, Ali Dinar proclaimed his loyalty to the Ottoman Empire and responded to the Porte's call for a jihad against the Allies.
In the first two decades of condominium rule, the British extended telegraph and rail lines to link key points in northern Sudan but services did not reach more remote areas.
In their view, it prevented the country's unification, exacerbated tribalism in the north, and in the south served to buttress a less-advanced society against Arab influence.
Indirect rule also implied government decentralization, which alarmed the educated elite who had careers in the central administration and envisioned an eventual transfer of power from British colonial authorities to their class.
Nationalists and the Khatmiyyah opposed indirect rule, but the Ansar (the followers of the Mahdi) supported the British approach since many of them enjoyed positions of local authority.
From the beginning of the Anglo-Egyptian condominium, the British sought to modernize Sudan by applying European technology to its underdeveloped economy and by replacing its authoritarian institutions with ones that adhered to liberal English traditions.
Southern Sudan's remote and undeveloped provinces—Equatoria, Bahr al Ghazal, and Upper Nile—received little official attention until after World War I, except for efforts to suppress tribal warfare and the slave trade.
The few southerners who received higher training attended schools in British East Africa (present-day Kenya, Uganda, and Tanzania) rather than in Khartoum, thereby exacerbating the north–south division.
The period's "closed door" ordinances, which barred northern Sudanese from entering or working in the south, reinforced this separate development policy.
Finally, a 1930 directive stated that blacks in the southern provinces were to be considered a people distinct from northern Muslims and that the region should be prepared for eventual integration with British East Africa.
Moreover, a continual struggle went on between British officials in the north and south, as those in the former resisted recommendations that northern resources be diverted to spur southern economic development.
Nationalists also perceived Britain's southern policy as artificially dividing Sudan and preventing its unification under an arabized and Islamic ruling class.
In 1921, Ali Abd al Latif, a Muslim Dinka and former army officer, founded the United Tribes Society that called for an independent Sudan in which power would be shared by tribal and religious leaders.
Three years later, Ali Abd al Latif's movement, reconstituted as the White Flag League, organized demonstrations in Khartoum that took advantage of the unrest that followed Stack's assassination.
Ali Abd al Latif's arrest and subsequent exile in Egypt sparked a mutiny by a Sudanese army battalion, the suppression of which succeeded in temporarily crippling the nationalist movement.
Although they settled most of their differences in the Anglo-Egyptian treaty of 1936, which set a timetable for the end of British military occupation, Britain and Egypt failed to agree on Sudan's future status.
The Mahdi's son, Abd al-Rahman al-Mahdi, emerged as a spokesman for independence in opposition to Ali al Mirghani, the Khatmiyyah leader, who favored union with Egypt.
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 Sudan at several points and captured the railway junction at Kassala and other villages along the border.
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.
Sir Douglas Newbold, governor of Kurdufan Province in the 1930s and later the executive council's civil secretary, advised the establishment of parliamentary government and the administrative unification of north and south.
In 1948, over Egyptian objections, Britain authorized the partially elected consultative Legislative Assembly representing both regions to supersede the advisory executive council.
After seizing power in Egypt and overthrowing the Faruk monarchy in late 1952, Colonel Muhammad Naguib broke the deadlock on the problem of Egyptian sovereignty over Sudan.
Naguib's concession seemed justified when parliamentary elections held at the end of 1952 gave a majority to the pro-Egyptian NUP, which had called for an eventual union with Egypt.
During World War II, some British colonial officers questioned the economic and political viability of the southern provinces as separate from northern Sudan.
In particular, they resented the imposition of Arabic as the official language of administration, which deprived most of the few educated English-speaking southerners of the opportunity to enter public service.
But this harsh reaction failed to pacify the south, as some of the mutineers escaped to remote areas and organized resistance to the Arab-dominated government of Sudan.