Operation Sea Wall

The 1961 Mock Invasion of San Juan Island

The Pig War wasn't the last time San Juan Island saw military action. In 1961, a mock invasion involving 12,000-14,000 military personnel and including the US Army, US Navy, and the US Air Force was held on the island.

In 1961, over a century after the events of the Pig War, San Juan Island was once again the site of military action. Rather than a tense standoff between two nations, the occasion this time was a military exercise—named “Sea Wall”—conducted by the US military. Operation Sea Wall was the first of three total training exercises as a part of a one year program conducted by the military. The other two exercises—”Great Bear” and ”Mesa Drive”—were held in Alaska and Yakima respectively.

The stage set by Operation Sea Wall cast San Juan Island as the fictitious Republic of Olympia which had been overrun and occupied by an aggressor force. Approximately 4,000-5,000 military personnel were designated as “Liberators” while other military personnel were designated as “Aggressors”. The Liberators’ mission was to storm South Beach and “liberate” San Juan Island from the Aggressors occupying the island.

The weeklong exercise began at midnight, September 7th. Around 12,000-14,000 total military personnel from the US Army, Navy, and Air Force were involved in the exercise with a naval fleet consisting of fourteen ships. In preparation for the impending invasion, driftwood was cleared from South Beach, the Aggressors dug foxholes, and roads were graded at multiple sites on the island. Once prepared, the Liberators stormed South Beach—delivered by landing craft from the Pacific Fleet—and skirmishes ensued for the following three days.

The exercise was a great spectacle to the islanders who had been blocked off from the exercise area. Schools were dismissed, most businesses were closed, and buses carried islanders to and from the bleachers set up at Mt. Finlayson for viewing the exercise. Buses left from the County Fairgrounds in Friday Harbor every morning, and each day saw over 2,000 spectators of the exercise. The islanders were technically an occupied population in this scenario, but when a squad of Aggressors rushed past a section of the bleachers, the “occupied population” showered the Aggressors with a round of applause. Despite the support from the occupied population, the Aggressors surrendered at the end of the three-day assault, and the Liberators emerged victorious as had been planned.