Before the Pearl Harbor attack, the Army allowed the Marines to emplace two gun batteries in northwest Fort Rosecrans for training purposes. Battery Gillespie consisted of 3 5-inch Navy guns.
Battery Gillespie was named for Marine Corps officer Lieutenant Archibald H. Gillespie who assisted Army Brigadier General Stephen Watts Kearny after the Battle of San Pasqual during the California Conquest.
Colonel P. H. Ottosen kept batteries Gillespie and Point Loma to support an antisubmarine mission for the harbor defense.