Fortifications and other 19th-century military installments commemorate the Pig War, in which the United States and Great Britain nearly went into battle over their respective claims on the San Juan Islands. The dispute began in 1859 when an American settler killed a British soldier's pig, and escalated until roughly 500 American soldiers and 2,200 British soldiers with five warships were poised for battle. Fortunately, no blood was spilled, and the disagreement was finally settled in 1872 in the Americans' favor, with Kaiser Wilhelm I of Germany as arbitrator.
The park comprises two separate areas on opposite sides of the island. English Camp, in a sheltered cove of Garrison Bay on the northern end, includes a blockhouse, a commissary, and barracks. A popular (though steep) hike is to the top of Young Hill, from which you can get a great view of northwest side of the island. American Camp, on the southern end, has a visitor center and the remains of fortifications; it stretches
along driftwood-strewn beaches. Many of the American Camp's walking trails are through prairie; in the evening, dozens of rabbits emerge from their warrens to nibble in the fields. Great views greet you from the top of the Mt. Finlayson Trail—if you're lucky, you might be able to see Mt. Baker and Mt. Rainier along with the Olympics. From June to August you can take guided hikes and see reenactments of 1860s-era military life.