While under Mexican rule, a fortification was constructed atop Presidio Hill overlooking Pueblo de San Diego, which is now Old Town San Diego. The fort was intended to guard the San Diego bay and protect the San Diego River basin. San Diego was a major port for the lucrative leather hide trade and whaling ships that would come into San Diego bay for supplies during their hunt for whales migrating along the west coast of North America. This fortification was abandoned in 1837, with but only the earthen foundation remaining.
As hostilities broke out in May 1846 and war declared with the Republic of Mexico, U.S. naval forces of the Pacific Squadron out of the Sandwich Islands (Hawaii) sailed up the Pacific coast to secure the major California ports of Monterey, San Pedro and San Diego and block west coast Mexican maritime commerce. On July 29, 1846, the 22-gun American corvette, USS Cyane, under the command of Captain Samuel F. DuPont sailed into San Diego bay. Aboard this naval war sloop in addition to its crew of 120 sailors and marines were Major John C. Frémont and 165 mountain men of the California Battalion, Kit Carson and five Delaware Indian scouts, who had boarded at Monterey. Lt. Stephen Rowan, USN, with a marine guard under the command of Lt. William Maddox, USMC, rowed ashore in the launch Alligator and commenced to raise the American flag on a mast flag pole at the Plaza San Diego Viejo. While at San Diego, the crew of the USS Cyane labored to reenforce the dilapidated structure atop Presidio Hill. The new fortification was named Fort DuPont in honor of Captain DuPont. After gathering up horses and supplies, Frémont and his troops left by land and the USS Cyane by sea to engage Mexican forces at Los Angeles.
Captain Ezekiel Merritt and John Bidwell of Frémont’s California Volunteers were left in charge of a small American garrison in San Diego. After the American forces led by Marine Lt. Archibald Gillespie were defeated at Los Angeles, Mexican Captain José Maria Flores gave orders to Francisco Rico, Serbulo Varela and a force of 50 Californio vaqueros to recapture San Diego. Upon learning of the advance by the Californio force, Merritt and Bidwell decided to abandon San Diego and Fort DuPont and took refuge aboard a small, smelly Yankee whaler, the Stonington, out of New London, CN, that was at anchor in the San Diego harbor for resupply. Bidwell and a crew of four in a small whale boat from the Stonington sailed north to San Pedro, the port for Los Angeles, seeking supplies and assistance from Captain William Mervine, USN, commander of the formidable 60-gun Navy frigate USS Savannah, but the Savannah was not in port. Because of the American departure, the Mexican flag flew again over San Diego.
Although Rico was recalled to Los Angeles, Varela continued south and led a band of loyal Californios who ransacked the San Diego ranchos for guns, knives, lances, ammunition and valuable horses, which DuPont had dubbed, “sinews of war.” Varela posted his mounted guerilla force along the ridge of Presidio Hill where they could fire down on the Plaza.
Armed with information from the Bidwell, the whaling ship Magnolia out of New Bedford, MA was chartered by the US government and set sail out of San Pedro for San Diego with 35 sailors and 15 volunteers to aid Merritt. They landed at the mouth of the San Diego River and formed a battle array that operated from the west end of town. With the placement of six 9-pounder brass cannons and their firearms at the ready, a 30-40 day siege commenced with some minor skirmishes. Eventually Varela’s forces withdrew from the siege site, but remained in the area. On October 26, 1846, Ramon Carrillo and Captain Leonardo Cota arrived at San Diego with 80-100 men under orders from General Flores to lay siege to San Diego and force the American combatants to surrender.
On October 31, 1846, Commodore Robert Stockton’s flagship, the 60-gun frigate, USS Congress, sailed into San Diego bay. Aboard were Captain Gillespie in command of 40 US Marines and California Volunteers to reenforce the besieged American forces from the Stonington and the Magnolia. Carrillo and his bravos charged the American line, but were repulsed with the aid of the 9-pounder cannonfire. A valiant assault of Presidio Hill led by local San Diegans, Santiago Arguello and Miguel de Pedrorena, who had aligned themselves with the Americans, drove the Californios from the hill and east up Mission Valley. The marines extended the operation to secure the town from the siege. San Diego was back under American control.
In order to prepare for a possible reassault on San Diego by hostile Californio forces, Stockton commenced to reenforce again the fortification atop Presidio Hill, previously called Ft. DuPont. According to Midshipman Robert Duvall the construction effort consisted of, “. . . 300 Gallon casks full of sand close together, 30 yds by 20 square throwing a Bank of earth and small gravel up in Front as high as the Top of the casks & running a Ditch around the whole. In the inside a Ball Proff house was built out of Plank lineing the inside with Adobes, on the top of which a swivel was mounted. The entrance was guarded by a Strong gate having a draw Bridge in front, the whole fortification was completed in about 3 weeks. Guns mounted and every thing complete notwithstanding the Plank, etc. had to be carried by the men near a mile and the ditch cut through a solid strata of gravel and rock, with but indifferent tools to do it with.”
This new reenforced fortification atop Presidio Hill was renamed Fort Stockton. It was essentially a broad ditch backed by sand-filled barrels with as many as 12 cannons (some reports say 7, others 17) guarding the San Diego River delta to the north and east and west overlooking the plaza of Pueblo de San Diego. Fort Stockton later came under the command of General Stephen Watts Kearny and the dragoons of the Army of the West in December 1846. The last military company assigned to Fort Stockton was Company B of the Mormon Battalion who relieved Kearny’s dragoons in March 1847 and took over garrison duty at Fort Stockton with its seven artillery pieces. The signing of the Treaty of Guadalupe Hidalgo on February 2, 1848 ended the Mexican War and Fort Stockton was completely abandoned as a US military post. Two surviving artillery pieces of Fort Stockton, a Spanish cannon cast in Manila in 1783, named El Cápitan, was placed at the Plaza and its sister cannon, El Jupiter, was located in the Presidio building, where they remain as reminders of this chapter of San Diego history.