In 1892 , the army began constructing the new Endicott System concrete fortifications armed with steel , breech-loading rifled guns . Within eight years , all 103 of the smooth-bore cannons at Fort Point had been dismounted and sold for scrap . The fort , moderately damaged in the 1906 earthquake , was used over the next four decades for barracks , training , and storage , however , in 1913 , part of the interior wall was removed by the army in their short-lived attempt to make the fort the army detention barracks using soldier and prisoner labor . The detention barracks were later built on Alcatraz Island and was used until becoming a federal prison . Soldiers from the 6th U.S. Coast Artillery were stationed there during World War II to guard minefields and the anti-submarine net that spanned the Golden Gate
1906 earthquake
1906 San Francisco earthquake
Fort Point, San Francisco