The conflict you’re looking for is the Pig War of 1859 , a bloodless border standoff between the United States and the United Kingdom that was triggered by the shooting of a pig on San Juan Island, in the Pacific Northwest.

Quick Scoop: What happened?

  • In June 1859, an American settler, Lyman Cutlar, shot a pig that kept wandering into his potato patch and eating his crops.
  • The pig belonged to Charles Griffin, an employee of the British Hudson’s Bay Company on San Juan Island, a territory then disputed between the U.S. and Britain.
  • What could have been a simple neighbor dispute escalated because both nations already claimed the island under vague wording in the 1846 Oregon Treaty, which left the exact marine boundary unclear.

Why people say it was “triggered by shooting a pig”

  • The pig’s death turned into an international incident when British authorities threatened to arrest the American farmer, and he asked the U.S. Army for protection.
  • The U.S. sent troops; Britain responded with warships. For a time, hundreds of U.S. soldiers faced several Royal Navy ships in a tense but restrained standoff.
  • Because the crisis only began in earnest after Cutlar shot the pig, the whole affair became known as the Pig War , sometimes also called the Pig and Potato War or the San Juan Boundary Dispute.

Was it a real “war”?

Technically, it was a bloodless confrontation , not a shooting war:

  • No human casualties occurred; the only casualty was the pig itself.
  • Commanders on both sides ultimately chose restraint, and the island remained under a joint U.S.–British military occupation for years until an international arbitration (by Kaiser Wilhelm I of Germany) finally awarded the San Juan Islands to the United States in 1872.

So, if you’re asking “which war was triggered by shooting a pig?” , the historically accurate answer is:
The Pig War (1859) between the United States and the United Kingdom, over the San Juan Islands in the Pacific Northwest.