In June 1859, American farmer Lyman Cutlar was living on San Juan Island, an island situated between the US mainland and Vancouver Island whose sovereignty was vaguely defined by the Oregon Treaty of 1846. Cutlar caught a large black pig belonging to Charles Griffin, an employee of the British Hudson's Bay Company, eating potatoes in his garden. Outraged, Cutlar shot and killed the pig.
When Cutlar offered to pay a modest sum as compensation, Griffin demanded a far higher amount and threatened arrest by British authorities. Spurred by patriotic defiance, Cutlar sought protection from the US Army. Captain George Pickett, later famous for his Confederate charge at Gettysburg, arrived with 66 American soldiers and declared the island US territory.
In response, British Governor James Douglas dispatched three warships under Royal Navy Captain Geoffrey Hornby, with orders to land marines. Pickett refused to back down, declaring they would fight to the last man. As troop numbers swelled to nearly 500 Americans and over 2,000 armed British personnel on warships, cooler heads prevailed.
Royal Navy Admiral Robert L. Baynes refused orders to escalate, famously remarking that starting a war between two great nations over a pig was foolish. When news reached Washington and London, leaders were horrified and quickly dispatched diplomats to institute a joint military occupation, which lasted peacefully for 12 years until an international arbitrator awarded the island to the US in 1872.