Why is Battery Cavallo So Unusual?

Historical Aerial photo of chevron-shaped Battery Cavallo near the waters edge.

Hidden behind this fence and earthen mounds is Battery Cavallo, one of the most outstanding examples of military architecture in Golden Gate's outdoor coast defense museum. Historian Erwin Thompson wrote of this battery...

Of all the coast defense works constructed in the 1870s, the Cavallo Battery is the most handsome architecturally and is the best surviving example of the post-Civil War earthworks batteries.

Battery Cavallo was constructed in the 1870s to replace the obsolete Civil War-era brick forts. This distinctive shield-shaped, earthwork and brick emplacement was to be armed with three monstrous 20-inch diameter Rodman cannon that would fire 1,000-pound projectiles four miles, as well as many additional 12-inch rifles, 13-inch mortars, 15-inch cannon.

Construction of Battery Cavallo began in 1872, but as was typical of many military projects of this era, money quickly dried up. Several years later, the structure stood nearly complete, but no guns were placed here until the Spanish American War of 1898, when three already obsolete 8-inch rifled Rodman guns were installed.

Today, this enclosure not only preserves this unique example of 1870s military architecture, but also protects critical grassland habitat for the endangered Mission blue butterfly.