• View of the Golden Gate Bridge, taken from the Marin Headlands, looking towards San Francisco at sunrise.

    Golden Gate

    National Recreation Area California

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  • Tunnel Closure

    The Barry/Baker tunnel on Bunker Road will be closed for maintenance during the weeks of 6/2 and 6/9. The tunnel will be open on the weekends. Please use Conzelman Road instead. More »

  • Muir Beach Overlook closure

    The Muir Beach Overlook will be closed for Accessibility improvements and trail upgrades from June 2 through July 21. Alternate viewpoints are available along Highway 1 between there and Stinson Beach.

An Integrated System of Guns

San Francisco's harbor defenses relied on a complex system of guns, underwater mines, and antisubmarine nets. Central to the system were guns of many sizes, each with its own purpose. These guns were classified by the diameter of the projectiles they fired.

photo of an antiaircraft gun
Rapid-fire three-inch (above) and 90 mm guns targeted aircraft and motor torpedo boats. Smaller 40 mm and various caliber machine guns were used as antiaircraft (AA) weapons.
San Francisco History Center, San Francisco Public Library

photo of gun firing
Mortars could fire 12-inch shells on a high arcing trajectory, thereby penetrating the lightly armored decks of ships. Mortars also could fire in all directions, making them useful during a ground invasion.  
PARC, Golden Gate National Recreation Area
a 6-inch gun at Battery Chamberlain
Six-inch guns, like this one at Battery Chamberlin, protected the offshore minefields. Mounted and mobile 155 mm guns also guarded the minefields and protected the beaches from landing craft.
San Francisco History Center, San Francisco Public Library
photo of Battery Townsley
Massive 16-inch guns at Battery Townsley (as seen above) and Davis defended against batteships that also had guns capable of firing shees up to 25 miles.
PARC, Golden Gate National Recreation Area
firing of Battery Wallace
Turn-of-the-century 10- and 12-inch guns and newer, high-powered 12-inch guns at Battery Wallace fended off armored warships in the 10 to 15 mile range.
San Francisco History Center, San Francisco Public Library

Did You Know?

Franklin Street at Fort Mason

By the 1850s, Fort Mason was established as a military installation and the buildings on Franklin Street, constructed between 1864 and 1913, are some of the earliest remaining buildings at Fort Mason.