Alcatraz Firepower

Alcatraz began as a U.S. Army fort designed to defend San Francisco Bay against enemy attack, and at the height of the Civil War the fortified island held over 100 heavy cannon. The largest were sleek Rodman guns on iron carriages, their distinctive soda bottle shape reflecting the pressures that built up inside the barrel during firing. Nicknamed after their inventor, Thomas Jackson Rodman, these guns were carefully designed and manufactured to be very safe to fire at a time when many cannon exploded without warning, and no Rodman ever did. Rodman cannon ranged from 8-inch caliber guns to 15-inch caliber models weighing nearly 50,000 pounds, and by 1869 the U.S. Army had shipped 39 Rodmans to Alcatraz Island. The last of Alcatraz's cannon were donated to a scrap drive in 1943. A typical 10-inch Rodman on an iron carriage, like dozens of guns on Alcatraz during the 1860s, was aimed, loaded, and fired by a crew of ten to twelve soldiers, who used large rear wheels to rotate the gun right or left on circular iron rails and smaller wheels to move the top carriage forward and back; when fired, the gun recoiled backward and up inclined iron rails until friction and gravity stopped it. Gun and carriage together weighed 20,500 pounds, its solid cannonball weighed 128 pounds, and with 15 pounds of powder it had a range of 2.75 miles.

San Francisco, California · United States