Def: a rebellion against the Khedivate of Egypt, and later the British by the Mahdist Sudanese in modern-day Sudan. Inspired by Islam, it was led by Muhammad Ahmad bin Abd Allah, who had proclaimed himself the "Mahdi" of Islam.
Sig: it was a decisive rebellion against the imperialist forces of Britain, but it resulted in the creation of the jointly-ruled state of Anglo-Egyptian Sudan, where the British and the Egyptians, where the British had de facto control over Sudan.