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
Legends of Alcatraz 25 Scariest Places in the World". Alcatraz Citadel, also known as Fort Alcatraz, was the original military defense and prison on Alcatraz Island. The citadel was built in 1859 as a U.S. Army military defense, and began function as a war camp in 1861 and long-term military prison in 1868. During the American Civil War, the citadel and its batteries provided an important line of defense. The island continued to develop in the 1870s and 1880s, and in 1893, the first hospital on Alcatraz opened. A new upper prison was built in 1904, but after the citadel ceased function as