On November 22 and 23, 1861, a fierce Civil War battle raged here as Union troops at Fort Pickens bombarded Confederates who had occupied Fort McRee across the bay and Fort Barrancas and the Navy Yard on the mainland. The Confederates fired back, but the Union, aided by cannon fire from two warships, heavily damaged the Navy Yard and nearly demolished Fort McRee. Needing troops elsewhere, the Confederates left the posts in the spring of 1862, and the Union moved most of its troops on Santa Rosa Island to the mainland.