The shortest war in history lasted just 38 minutes. The Anglo-Zanzibar War in 1896 came about after a British-supported Sultan in Zanzibar died of suspicious causes.
The Anglo-Zanzibar War came at the height of European colonialism in Africa. In 1890, Germany and Britain signed a peace treaty that divided up their African colonies. One of these territories, Zanzibar, belonged to the British. To keep a watch over the region, Britain installed a "puppet" sultan, Hamad bin Thuwaini, as ruler.
For three years, Hamad's rule went smoothly until he died in his palace of unknown and suspicious causes. Adding to the intrigue, Hamad's cousin, Khalid bin Harghash, immediately claimed the sultanship. Theories of foul play spread throughout Zanzibar and Britain.
The British disliked Khalid and didn't want him in power, so they aggressively "asked" him to step down. Khalid ignored Britain's requests, which later grew to demands and ultimatums. Rather than back down, Khalid built an army, gathering even the artillery that was a gift from the British. Meanwhile, the British navy assembled in the harbor near Khalid's palace.
British diplomat Basil Cave continued to issue stern ultimatums and, eventually, outright threats. Khalid boldly replied: "We have no intention of hauling down our flag and we do not believe you would open fire on us." He was very, very wrong.
At 9 a.m., the British began shelling Khalid’s compound. By 9:02 a.m., most of Khalid's artillery was destroyed, and his palace began to collapse. By 9:40 a.m., the Sultan's flag was pulled down and Britain stopped attacking, but not before Khalid escaped through the palace’s back exit. He eventually made it to safety in Germany.
By the end of the 38 minutes, Khalid's forces suffered 500 casualties, and just one British officer was injured. Shortly after its victory, Britain installed another puppet sultan, and all was returned to "normal."