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
Battle of Alcatraz cellblock. Joe Cretzer was a west coast gangster and member of the Cretzer-Kyle Gang. In 1940 he was sentenced to 25 years for murder. After two escape attempts in the first months of his incarceration, one of which resulted in another murder charge, he was transferred to Alcatraz. In May 1941, Cretzer, Shockley and two other convicts made an escape attempt from one of the prison's workshops. Carnes was the youngest prisoner to reside at Alcatraz, having been convicted of murder in 1943 at the age of 16. He made a number of escape attempts and by 1946, when he