In 1859, a single pig nearly triggered an international conflict between the United States and United Kingdom. The incident, now known as the Pig War, took place on the San Juan Islands, a group of islands whose ownership was disputed after an earlier treaty failed to define the U.S.-British border clearly.

The confrontation began when American settler Lyman Cutlar discovered a pig repeatedly rooting through his potato patch. Frustrated after chasing it away several times, he shot the animal. The pig belonged to Charles Griffin, who demanded compensation. When the dispute escalated and British authorities threatened to arrest Cutlar, American settlers appealed to the U.S. military for protection.

The situation quickly grew far beyond a disagreement over livestock. The United States dispatched soldiers under George Pickett, while Britain responded by sending several Royal Navy warships to the area. At one point, hundreds of American soldiers and thousands of British sailors faced one another across the islands. Remarkably, despite the tense military buildup, both sides exercised restraint, and no shots were fired between the opposing forces. The only casualty of the entire conflict remained the unfortunate pig.

Rather than resorting to war, the two nations agreed to a joint military occupation of the islands. For the next 12 years, American and British forces lived side by side, often maintaining cordial relations despite representing rival governments. The unusual arrangement became one of the most peaceful military standoffs in history.

The dispute was finally settled in 1872, when Wilhelm I was asked to arbitrate the boundary. He ruled in favor of the United States, awarding the San Juan Islands to American territory.