Just east of the American Camp visitor center, within easy walking distance, is what at first appears to be a modest hillock, its crest giving on to skyline. However, once there it's instantly apparent that one is standing on the ramparts of a fortification fashioned by human hands. And laid out from the far ditch of the structure to the slopes of Mt. Finlayson is an astounding sweep of open prairie flanked, less than a mile apart, by the Strait of Juan de Fuca and Griffin Bay.
This is Robert's Redoubt, the commanding position ordered at the height of the Pig War crisis of 1859 by U.S. Army officials at Vancouver Barracks to establish an American deterrent to the three British warships (with 64 total guns) anchored in the bay. And it served notice that the Americans intended to remain on San Juan Island for as long as it was required to back the United States' claim to the San Juan Archipelago.
Today the redoubt is one of the best preserved fortifications of its kind in the nation and continues to stand sentinel of over prairieland and saltwater shore, though instead of warships these days visitors are alert for bald eagles and red fox hunting the grasslands or hopefully will spot orca whales breeching off shore.
Getting on in years and deeply religious, Casey was horrified by the prospect of open hostilities with the British. He was well aware of the power of the Royal Navy. His forces had been dispatched to the island by Harney to protect United States citizens from the British, who Harney believed were claiming sovereign jurisdiction over a disputed territory. The long-festering issue had flared into armed confrontation in June when an American settler had shot a pig belonging to the Hudson's Bay Company. The company wanted fair restitution. The settler thought they wanted to jail him. Everyone overreacted —most especially Harney.
General Harney took Casey at his word and, in the spirit of Vauban, on August 16 dispatched to San Juan Island a 10-man detachment (called a sapper team) of Company A, U.S. Army Corps of Engineers, commanded by 2nd. Lt. Henry Martyn Robert. Robert was to report to Casey, who would place him in charge of creating a fortification for the naval guns, as per Harney's instructions, which had been relayed by the department's acting Adjutant General, Capt. Alfred Pleasonton (later to achieve fame as a Union cavalry officer in the Civil War).
Casey already had taken delivery of large quantities of lumber "fit for gun platforms," which the British Capt. Geoffrey Phipps Hornby, RN, noted was being stockpiled on the beach. Hornby commanded the 31-gun steam frigate HMS Tribune, anchored in Griffin Bay for nearly two weeks. The naval guns had been wrestled into place on the ridge overlooking Griffin Bay, while the camp had been moved from the exposed prairie above South Beach to just north of the Hudson's Bay Company farm.
Capt. James Prevost, RN, commander of HMS Satellite, reported that the new camp “is very strongly placed in the most commanding position on this end of the island, well sheltered in the rear and on one side by the Forest, and on the other side by a Commanding eminence.”
Casey said “...I shall put my heavy guns in position to bear upon the harbor, and also on vessels which might take a position on the other side. Shells from shipping may be able to reach us, and we may not be able to protect the camp from them; but I shall try.” The sight of these preliminary works alarmed Hornby enough to dash off a dispatch to his superior, Rear Adm. R. Lambert Baynes, RN, commander of the British Pacific Station squadron based in Victoria.
“Six of their heavy guns are placed on the ridge of the hill overlooking the harbour; and by throwing up a parapet they would command the harbour; even in their present position they would be difficult to silence,” Hornby wrote. As the son of an Admiral-of-the-Fleet and an experienced 19th-century military man in his own right, Hornby recognized how construction of a formal field work could alter the situation on San Juan Island. He knew that a fortress not only provided a means of last ditch defense, but sited in a strategically dominant position, would permit a smaller force -- even with inferior troops -- to resist a larger one long enough for more substantial resistance to be mounted. Once dug in, the Americans might never be uprooted and the island would be lost, politically as well as militarily.
Robert and his crew landed on August 21 and almost immediately went to work, supplemented by details from Casey’s infantry and artillery companies. According to the diary of William A. Peck, Jr., one of Robert’s soldiers, the fort was “laid out of an irregular form 425 feet long above the natural ground; ditch 20 feet wide, not less than 8 feet deep.”
As Captain Prevost reported, “...the hill south of the American Camp, has been marked out for fortifying, in several places it has been leveled, and working parties have lately been employed in throwing up earthworks.” The British Colonist estimated that at least 100 men were designated for the task, including one British subject who had been apprehended for liquor selling. It all was done with pick and shovel, which presented a challenge for the men, who had to clear enormous rocks left in the wake of glaciers that had receded thousands of years before.
Last updated: April 19, 2021