| Conflict: | Battle of La Mesa |
| Partof: | the Conquest of California during the Mexican–American War |
| Date: | January 9, 1847 |
| Place: | Rancho San Antonio, Alta California, Mexico(battlefields now parts of) Los Angeles River Modern Cities:Vernon,CA |
| Coordinates: | 34.0024°N -118.2048°W |
| Result: | American victory |
| Combatant1: |  United States |
| Combatant2: | Mexico |
| Commander1: | Robert F. Stockton Stephen Watts Kearny |
| Commander2: | José María Flores |
| Strength1: | 607 |
| Strength2: | 300 |
| Casualties1: | 1 killed 5 wounded |
| Casualties2: | 1 killed 20+ wounded |
The Battle of La Mesa (also known as the Battle of Los Angeles) was the final battle of the California Campaign during the Mexican–American War, occurring on January 9, 1847, in present-day Vernon, California, the day after the Battle of Rio San Gabriel.[1] The battle was a victory for the United States Army under Commodore Robert F. Stockton and General Stephen Watts Kearny.
Not finding any Californians at Governor Pío Pico's ranch, the Americans under Stockton and Kearny crossed the plain between the San Gabriel River and the Los Angeles River called La Mesa.[2] They encountered José María Flores' 300-strong force of Californio militia, including artillery, near where the city of Vernon now stands, about four miles south of Los Angeles.
The Californian guns were ineffective, while the American guns responded from their square as the Americans advanced. Flores extended his line and brought up two more guns. Stockton halted and formed his guns into a single battery. After fifteen minutes, Stockton's fire drove the Californian artillery from effective range. Flores sent his lancers against the American left flank but were driven back; most of his men deserted, allowing the Americans to advance into Los Angeles.
The battle was the last armed resistance to the American conquest of California, and General José María Flores returned to Mexico afterward. Three days after the battle, on January 12, the last significant group of residents surrendered to U.S. forces. The conquest and annexation of Alta California was settled with the signing of the Treaty of Cahuenga by U.S. Army Lieutenant-Colonel John C. Frémont and Mexican General Andrés Pico on January 13, 1847.
The site of the battle is now registered as California Historical Landmark #167. The marker is located at 4490 Exchange Avenue at Downey Road in Vernon.
California Historical Landmark Marker No. 167 at the site reads:[3]
. Hubert Howe Bancroft. Hubert Howe Bancroft. History of California, 1846–1848. XXII. 1886. History Company. 395.