Fort Pickens is the largest of four forts built to defend Pensacola Bay and its navy yard. Major William Henry Chase, U.S. Army Corps of Engineers, supervised the project. The fort was begun in 1829, completed in 1834, and used until 1947. Over 21.5 million bricks were required, most made locally and barged to the island. Underhill and Strong of New Orleans provided a work force of skilled African-American slave labor to construct the fort. Construction of the fort was extremely difficult. Workers were exposed to an unfriendly climate, yellow fever, and experienced heat exhaustion. Major Chase was frustrated by delays in appropriations from Congress plus the sale of bootleg whiskey to soldiers.