The shortest war in history lasted only 38 minutes - Apparently.
On August 27, 1896, the British ship HMS Philomel was sent to Zanzibar to demand that the local sultan, Hamad bin Thuwaini, accept British protection. The sultan refused, and the British began shelling the city. After 38 minutes, the sultan agreed, and the war was over. This brief conflict is recognized by the Guinness World Records as the shortest war in recorded history.