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
June 1962 Alcatraz escape attempt to death by guards because he wouldn't help investigators locate his brothers. A 2014 study of the ocean currents by scientists at Delft University and the research institute Deltares indicates that if the prisoners left Alcatraz at 11:30 pm on June 11, they could have made it to Horseshoe Bay just north of the Golden Gate Bridge, and that any debris that were released into the bay would have floated into the direction of Angel Island, consistent with where the paddle and belongings of the prisoners' was actually found. A 2015 History Channel documentary presented further circumstantial evidence gathered over