A single dead pig nearly started a war between the US and Britain

In 1859, an American farmer on a disputed island shot a British-owned pig for rooting in his garden. Both nations rushed troops and warships to the San Juan Islands, and for a moment two empires stood on the brink of war over one pig. Cooler heads prevailed — the British commander refused to 'involve two great nations in a war over a squabble about a pig' — and the two sides jointly occupied the islands peacefully for the next 12 years.

— Standard historical accounts, Pig War (1859) — San Juan Islands boundary dispute, 1859–1872