Fort Cronkhite, on the Marin Headlands, is a historic US Army facility that supported Battery Townsley, part of San Francisco Bay‘s coastal artillery during World War II, about 8 miles southwest of Stinson Beach and 8 miles west-northwest of San Francisco, California. The Marin Headlands, at the southern tip of the Marin Peninsula, consist of rock formations created by oceanic sediments from the Pacific Plate accreting onto the North American Plate. Graywacke sandstone, radiolarian chert, serpentinite, pillow basalts, and shale comprise the Franciscan Complex, which migrated north along the San Andreas Fault from near present-day Los Angeles over the past 100 million years. The Coast Miwok lived in the Headlands for thousands of years before European contact, moving freely between bay and ocean. In 1776, Spanish settlers arrived in the San Francisco Bay area to establish garrisons, missions, and settlements. Most Coast Miwok relocated to the San Francisco mission and converted to Christianity; they are now federally recognized as the Federated Indians of Graton Rancheria. Following the Mexican War of Independence in 1821, Spanish mission lands were secularized and granted as private ranchos. In 1838, Governor Juan Alvarado awarded a 19,752-acre land grant called Rancho Saucelito, meaning ‘ranch of the little willow grove,’ to Captain William A. Richardson. The grant stretched from the Pacific Ocean to Mount Tamalpais and included Arroyo Corte Madera del Presidio and Richardson Bay. Richardson’s poor investments led to mounting debts. In 1856, weakened by ill health, he transferred the estate to Samuel R. Throckmorton, who sold parcels to settle obligations. Lands north of Rodeo Lagoon later became part of the Marin Land and Cattle Company’s dairy farm. The Headlands’ favorable climate once supported thriving dairies. By the 1880s, Marin County was California’s largest producer of fresh milk and butter, a success fueled by Portuguese immigrants from the Azores. The site’s strategic view of the Golden Gate was long prized by military planners.

In 1866, the US acquired lands on the Marin Headlands for military defense, to house Forts Baker and Barry. In 1914, the adjacent Tennessee Point Military Reservation near Fort Barry was added. In 1928, the Army’s adjutant general announced plans to build two coastal defense gun batteries—one on each side of the Golden Gate. These fortifications were designed to complement those at the Presidio of San Francisco, preventing hostile ships from entering the bay. In 1937, Congress approved the expenditure, and the Army acquired about 800 acres (324 ha) north of Rodeo Lagoon from the Marin Land and Cattle Company. The new reservation was named Fort Cronkhite in honor of Major General Adelbert Cronkhite, commander of the 80th Division, National Army, during World War I. Fort Cronkhite formed part of the 6th Air Defense Artillery Regiment—Harbor Defense of San Francisco, headquartered at Fort Winfield Scott in the Presidio. In the fall of 1939, with only 200,000 enlisted soldiers, the Army had little need for new housing. However, beginning in 1940, as hundreds of thousands of draftees entered the Army and Navy, military ranks swelled and fresh accommodations became necessary. The rapid buildup necessitated tens of thousands of temporary wooden structures to house the expanding force. The Army’s Quartermaster Corps and Corps of Engineers oversaw construction projects nationwide, and standardized plans allowed the swift erection of barracks, mess halls, supply depots, chapels, and recreation facilities. Many of these wooden structures were built at Fort Cronkhite, which first housed Battery E of the 6th Air Defense Artillery in June 1941. Despite the barracks, the 150 soldiers manning Battery Townsley atop Wolf Ridge lived inside the gun bunker. This rapid construction not only met wartime exigencies but also exemplified the Army’s ability to mobilize and adapt its infrastructure quickly. Thus, Fort Cronkhite and its associated installations played a crucial role in fortifying the San Francisco Bay area during World War II, reflecting a period of swift military expansion and innovative logistical response.

Battery Townsley was a casemated gun installation that mounted two 16-inch, 50 caliber Mark II M1 Seacoast Rifles, each capable of firing a 2,100‑pound (953 kg) armor‑piercing projectile up to 25 miles (40 km) out to sea. The guns, along with their ammunition magazines, power rooms and crew quarters, were shielded by dozens of feet of concrete and earth to protect them from air and naval attack. Named for Major General Clarence P. Townsley—a World War I veteran and former West Point commandant—the battery epitomized contemporary military technology and long‑term strategic planning. As early as 1915 the Army sought to build 16‑inch gun batteries in San Francisco, and by 1928 plans were in place to install two batteries on either side of the Golden Gate. In 1938 construction began on this high‑security installation in the Marin Headlands, though its precise location was kept secret from San Francisco civilians. Despite months of intensive training under challenging conditions, the battery was never fired in combat. In 1943 radar enhanced the effectiveness of the 16‑inch and nearby antiaircraft guns by detecting approaching ships and aircraft, yet by war’s end long‑range bombers, missiles and nuclear weapons had rendered the installation obsolete—a testament to the rapid pace of military innovation. During the 1950s Korean War soldiers occupied Fort Cronkhite. In the Cold War era of the 1960s and early 1970s the facility supported operations at the Nike SF-88 missile site, one of 300 nationwide. By 1974, as the Nike sites in the Marin Headlands closed, the Army began deactivating the post. Today, Fort Cronkhite forms part of the Golden Gate National Recreation Area, hosting the National Park Service and supporting various nonprofit, educational and environmental partners. Battery Townsley remains a striking reminder of a time when massive coastal defenses were a military priority, reflecting the strategic mindset that shaped America’s wartime preparedness. See a short video on Battery Townsley here. Read more here and here. Explore more of Fort Cronkhite and the Marin Headlands here: