Battery Chamberlin, Military fortification at Baker Beach, San Francisco, United States.

Battery Chamberlin is a historic artillery battery at Baker Beach in San Francisco, California, made up of several concrete gun emplacements cut into the cliffs above the Pacific Ocean. The site faces the mouth of San Francisco Bay and includes underground cartridge rooms that are now used as exhibit spaces.

Built in 1904 with four six-inch guns on disappearing carriages, the battery guarded underwater minefields outside the Golden Gate. Its original guns were removed in 1917 for World War I; two six-inch guns on simple barbette carriages arrived in 1920. Battery D of the Sixth Coast Artillery manned them through World War II, and they were removed in 1948.

Battery Chamberlin is named for Captain Lowell A. Chamberlin, a Civil War officer. The National Park Service manages the site within the Golden Gate National Recreation Area, and on the first full weekend of each month, from 11 a.m. to 3 p.m., volunteers operate the 1905 disappearing gun so visitors can watch it rise and lower.

Access to the site is from the north end of Baker Beach parking area, where a short path leads directly to the gun emplacements. The underground exhibit rooms are open on weekends, and the paved paths make the site easy to walk for most visitors.

The disappearing gun preserved here was designed to sink behind a concrete parapet after firing, hiding it from enemy fire before it rose again to reload. The full lifting mechanism remains intact and is still moved regularly, so visitors can see exactly how the system worked in practice.