Fort Barrancas, built primarily by slave labor between 1839 and 1844, was one of four fortifications protecting Florida's Pensacola Bay and the U.S. Navy Yard from enemy attack. Fort Pickens on Santa Rosa Island and Fort McRee on Perdido Key guarded the channel. Fort Barrancas and its water battery, situated on a bluff facing the harbor entrance, could support their crossfire and fire shots at ships that entered the bay and harbor. Ironically, during the Civil War the Confederates briefly held Fort Barrancas and exchanged gunfire with Federal forces at Fort Pickens on November 22 and 23, 1861. According to Confederate General Braxton Bragg, "the action would rank with the heaviest bombardments in the world." In May of 1862, the Confederates withdrew to join forces elsewhere in the South and the Union forces reoccupied Fort Barrancas.