10 Wars That Were Started For Stupid Reasons
7. Bird Droppings (Spain Vs. Peru, 1864-1866)
If you were to try to think up the most idiotic commodity to go to war over, actual fecal matter would probably be quite near the top of the list. That didn't stop Spain from starting a war against various South American nations over heaps of literal poo.
The Spanish landed on the Chincha Islands in April 1864. The only notable feature of these islands, which were claimed by Peru, was that birds really, really loved defecating on them. The islands' reserves of guano were valuable as a fertiliser, but the Spanish mainly wanted it to show they didn't think Peru was a proper country and they could take stuff from Peru's islands whenever they wanted.
Peru disagreed, as did Chile, Ecuador, and Bolivia, and boom, that's how you make a war. After a few naval battles both sides claimed to have won and the Spanish fleet sailed home claiming to have taught those greedy poop-hoarders a lesson.