Alcatraz Island the hands of Confederate sympathizers. Alcatraz, built as a "heavily fortified military site on the West Coast", formed a "triangle of defense" along with Fort Point and Lime Point, and ensured security to the bay. The island was also the site of the first operational lighthouse on the West Coast of the United States. Alcatraz never fired its guns offensively, though during the war it was used to imprison Confederate sympathizers and privateers on the west coast. Because of its isolation from the outside by the cold, strong, hazardous currents of the waters of San Francisco Bay, Alcatraz was used
Alcatraz Federal Penitentiary Alcatraz Federal Penitentiary The Alcatraz Federal Penitentiary or United States Penitentiary, Alcatraz Island (often just referred to as Alcatraz or The Rock) was a maximum high-security federal prison on Alcatraz Island, off the coast of San Francisco, California, which operated from August 11, 1934, until March 21, 1963. The main prison building was built in 1910–1912 during its time as a United States Army military prison; Alcatraz had been the site of a citadel since the 1860s. The United States Disciplinary Barracks, Pacific Branch on Alcatraz had been acquired by the United States Department of Justice on October 12, 1933,