Alcatraz Island Engineers began fortifying the island, work which continued until 1858, eventuating in Fortress Alcatraz. The island's first garrison at Camp Alcatraz, numbering about 200 soldiers and 11 cannons, arrived at the end of that year. When the American Civil War broke out in 1861, the island mounted 85 cannons (increased to 105 cannons by 1866) in casemates around its perimeter, though the small size of the garrison meant only a fraction of the guns could be used at one time. At this time it also served as the San Francisco Arsenal for storage of firearms to prevent them falling into
Alcatraz Federal Penitentiary Robert Franklin Stroud (the "Birdman of Alcatraz"), George "Machine Gun" Kelly, Bumpy Johnson, Rafael Cancel Miranda, Mickey Cohen, Arthur R. "Doc" Barker, Whitey Bulger, and Alvin "Creepy" Karpis (who served more time at Alcatraz than any other inmate). It also provided housing for the Bureau of Prisons' staff and their families. A total of 36 prisoners made 14 escape attempts during the 29 years of the prison's existence, the most notable of which were the violent escape attempt of May 1946 known as the "Battle of Alcatraz", and the arguably successful "Escape from Alcatraz" by Frank Morris, John Anglin, and