The Anglo-Zanzibar War was a military conflict fought between the United Kingdom and the Sultanate of Zanzibar on 27 August 1896. The conflict lasted between 38 and 45 minutes, marking it as the shortest recorded war in history. The immediate cause of the war was the suspicious death of the pro-British Sultan Hamad bin Thuwaini on 25 August 1896 and the subsequent succession of Sultan Khalid bin Barghash. The British authorities preferred Hamoud bin Mohammed, who was more favourable to British interests, as sultan. The agreement of 14 June 1890, instituting a British protectorate over Zanzibar, specified that a candidate for accession to the sultanate should obtain the permission of the British consul; Khalid had not fulfilled this requirement. The British considered this a casus belli and sent an ultimatum to Khalid demanding that he order his forces to stand down and leave the palace. In response, Khalid called up his palace guard and barricaded himself inside the palace.

The Sultanate of Zanzibar, also known as the Zanzibar Sultanate, was an East African Muslim state controlled by the Sultan of Zanzibar, in place between 1856 and 1964. The Sultanate's territories varied over time, and after a period of decline, the state had sovereignty over only the Zanzibar Archipelago and a 16-kilometre-wide (10 mi) strip along the Kenyan coast, with the interior of Kenya constituting the British Kenya Colony and the coastal strip administered as a de facto part of that colony.