I'm pretty sure the stupidest war ever was the War of Jenkins' Ear, which not only was dumb in it's own merit but also spawned two additional wars that killed close to 2 million people.

Basically Britain and a trading company decided that a little war would help to spur trade, so they seized on an 8 year old incident involving the Spanish boarding a ship and cutting off the captain's ear to fan the flames of conflict.

While the casualties of this little conflict were only around 30k dead or wounded, and a paltry 500 ships, it nicely helped kick off the War of Austrian Succession. That fun conflict led to around half a million dead.

Not satisfied, the powers of Europe stewed over the previous two incidents and then decided to really get down and dirty. The Seven Years war was the first really 'global' war, involving every European great power of the time and spanning five continents. Roughly 1.25 million people got to shuffle their mortal coil off the world thanks, in part, to a little trade war over an ear.

If you want to see a live specimen of the sort of rotter responsible have a jolly old look at Uk foreign secretary and part time clown Boris Johnson. He has helped me understand the British Empire no end.

Moving this video to nanrod's personal queue. It failed to receive enough votes to get sifted up to the front page within 2 days.

1888: "Some damned foolish thing in the Balkans."

2018: "Some damned foolish thing in the Middle East."