The Battle of Omdurman was fought during the Anglo-Egyptian conquest of Sudan between a British–Egyptian expeditionary force commanded by British Commander-in-Chief (sirdar) major general Horatio Herbert Kitchener and a Sudanese army of the Mahdist Islamic State, led by Abdullah al-Taashi, the successor to the self-proclaimed Mahdi, Muhammad Ahmad. The battle took place on 2 September 1898, at Kerreri, 11 kilometres (6.8 mi) north of Omdurman in the Sudan.

Following the establishment of the Mahdist Islamic State in Sudan, and the subsequent threat to the regional status quo and to British-occupied Egypt, the British government decided to send an expeditionary force with the task of overthrowing the Khalifa. The commander of the force, Sir Herbert Kitchener, was also seeking revenge for the death of General Gordon, killed when a Mahdist army had captured Khartoum thirteen years earlier. On the morning of 2 September, some 35,000–50,000 Sudanese tribesmen under Abdullah attacked the British lines in a disastrous series of charges; later that morning the 21st Lancers charged and defeated another force that appeared on the British right flank. Among those present was 23-year-old soldier and reporter Winston Churchill as well as a young Captain Douglas Haig.The victory of the British–Egyptian force was a demonstration of the superiority of a highly disciplined army equipped with modern rifles, machine guns, and artillery over a force twice its size armed with older weapons, and marked the success of British efforts to re-conquer the Sudan. Following the Battle of Umm Diwaykarat a year later, the remaining Mahdist forces were defeated and the Anglo-Egyptian Sudan was established.