The shortest war in history lasted 38 minutes - Apparently.
The Anglo-Zanzibar War was fought between the United Kingdom and Zanzibar on August 27, 1896. The war was sparked by a dispute over who should be the ruler of Zanzibar, and it began when the British issued an ultimatum to the Zanzibari forces. After a 38-minute bombardment, the Zanzibari forces surrendered, and the war came to an end. The British had demanded that Zanzibar be ruled by a British-resident, but the pro-British Sultan was overthrown, prompting the British to declare war.