Alcatraz Citadel Bay and California State could be taken under its fold was thwarted. Alcatraz was officially designated as a military prison on August 27, 1861. In March 1863, when there was a threat that the San Francisco Bay would be captured by the Confederates, the schooner, which was to carry out the operation set sail; the U.S. Navy prevented the schooner from moving out and captured the crew along with ammunition and 15 confederates who were hiding in the galleys of the ship. Consequent to this, the importance of Alcatraz increased, more and more confederates and civilians were arrested for reasons
Alcatraz Island 1906 San Francisco earthquake, civilian prisoners were transferred to Alcatraz for safe confinement. On March 21, 1907, Alcatraz was officially designated as the Western U.S. Military Prison, later Pacific Branch, U.S. Disciplinary Barracks, 1915. In 1909 construction began on the huge concrete main cell block, designed by Major Reuben Turner, which remains the island's dominant feature. It was completed in 1912. To accommodate the new cell block, the Citadel, a three-story barracks, was demolished down to the first floor, which was actually below ground level. The building had been constructed in an excavated pit (creating a dry "moat") to enhance