Alcatraz Citadel having some 111 cannons encircling the island at peak, and was also used as a war camp. During the Civil War, the defense establishment at Alcatraz Citadel had the onerous task to defuse the possibility of any local war between the Union and Confederate supporters who were both part of the population of California, and to protect San Francisco. Ammunition in the form of 10,000 muskets and 150,000 cartridges was supplied to the fort, which made the Fort Alcatraz and the island most impregnable and thus leaving any plans of the Confederate soldiers of taking control of the San Francisco
Alcatraz Citadel coves and bay. In 1882, the citadel was enlarged to provide more accommodation for the families of the military officers working on Alcatraz. Between 1873 and 1895, 32 Native Americans were imprisoned at the citadel on Alcatraz, including 19 Hopi men held in captivity there between January and August 1895 after being transferred from Fort Defiance. The island continued to develop in the 1880s and in 1898 the population of Alcatraz increased dramatically from 26 to over 450 due to the Spanish–American War and placed a demand for new buildings. The original barracks evolved into Building 64 in 1905. The