Pig War (1859)

Pig War
	; — San Juan Islands ; — USA ; — UK ; — Border proposed by the USA ; — Border proposed by the UK ; — Compromise proposal ; — Modern border
Date	June 15 – October 1859 (troops stationed on San Juan Island until 1874)
Location	San Juan Islands48°27′42″N 123°00′24″W / 48.46167°N 123.00667°W
Result	A bloodless war—San Juan Islands awarded to the United States following third-party arbitration by the German Empire.
Belligerents
United States Washington Territory;	United Kingdom Colony of Vancouver Island;
Commanders and leaders
Silas Casey; William S. Harney; George Pickett;	James Douglas; R. L. Baynes; Geoffrey Hornby;
Strength
461 combatants, 14 cannons	2,140 combatants; 5 warships mounting 70 cannons

Vancouver's 1798 map, showing some confusion in the vicinity of southeastern Vancouver Island, the Gulf Islands, and Haro Strait

The Pig War was a confrontation in 1859 between the United States and the United Kingdom over the British–U.S. border in the San Juan Islands, between Vancouver Island (present-day Canada) and the Washington Territory (present-day State of Washington). The Pig War, so called because it was triggered by the shooting of a pig, is also called the Pig Episode, the Pig and Potato War, the San Juan Boundary Dispute, and the Northwestern Boundary Dispute. Despite being referred to as a "war", there were no human casualties on either side.