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
Occupation of Alcatraz Movement noted from their visit to the occupation that the demonstration garnered national attention, while those involved faced no punitive action. When AIM members seized the Mayflower II on Thanksgiving, 1970, the Occupation of Alcatraz was noted as "the symbol of a newly awakened desire among Indians for unity and authority in a white world." The occupation of Alcatraz Island served as a strong symbol and uniting force for indigenous peoples everywhere because of the importance the island held in their ancestors' lives. Indians traveled to Alcatraz about 10,000 years before the Europeans even entered the Bay area. Over the