Locals know Baker Beach for sunbathing and Golden Gate Bridge views. But there is a hidden relic here that recalls a time when the Pacific coast was the Army post's first line of defense – Battery Chamberlin. Built in 1904 to defend San Francisco's underwater minefields, the battery houses a 50-ton, six-inch diameter "disappearing gun." Once a month, the National Park Service invites visitors to experience this remnant of the past by actually loading and aiming the massive weapon.
Battery Chamberlin is one of 17 gun batteries that dot the Presidio's rugged coast. It originally housed four "disappearing guns." The weapon got its name from its innovative design – it's mounted on a carriage that lowers while it's being loaded to protect it from attackers. The gun could shoot two rounds a minute within a range of nine miles and took about 25 soldiers to handle – the shells alone weighed 100 pounds each. You'll be glad to know that the rounds used at the public demonstrations are lighter wooden replicas of the originals.
During World War I, the disappearing guns were removed to be used in Europe. In 1920, they were replaced by two six-inch guns on simple barbette carriages that were later manned in World War II. These were removed in 1948 when the Coast Artillery Corps was called out of service.
Visit Battery Chamberlin
The disappearing gun you'll see today at Battery Chamberlin is a gift from the Smithsonian Institution, which donated it to the National Park Service in 1977 for demonstration purposes. Made in 1905, it's very similar to the original. It is the only remaining disappearing gun on the West Coast.
The demonstration is free and takes place on the first full weekend of every month from 11 am to 3 pm. Battery Chamberlin is located at the north end of the Baker Beach parking lot. After the short demonstration, explore the small seacoast defense museum inside the battery's underground cartridge room, where you'll see photos and exhibits showcasing the other coastal defenses of San Francisco Bay.