Flank Defense Howitzer

This material is from the display board located adjacent to the howitzer gun inside the sally port.

Mighty and far reaching firepower

In 1866, Alcatraz's sole role was to protect San Francisco and the army had emplaced one hundred and eleven cannon along the island's perimeter. The fort's Rodman guns could shoot 440-pound cannonballs three miles. The smallest artillery guns, howitzers, were loaded with canisters of small balls. Had hostile troops stormed up the road from the dock, the guardhouse howitzers would have torn them to pieces.

Booming development in San Francisco, sparked by the Gold Rush, made military defense of the city a top priority.

Map of Alcatraz with artillery battery placements shown.

Gun batteries were positioned to defend the harbor and city against invaders who never came.

Photo of gun emplacement along shore

Alcatraz's largest cannon were mounted in open batteries on the west side of the island, facing the Golden Gate.

Very large gun with 12 men standing around

Alcatraz's Rodman guns weighed 50,000 pounds each and required a crew of more than a dozen men. Though there were more than 400 soldiers on the island in 1865, the men would have to move between the fort's cannon, depending upon the enemy's location, had the island been attacked.