On September 23 about fifty Mexican residents of Los Angeles surrounded the small Army garrison there and proclaimed a rebellion against American rule. The episode was the latest twist in a turbulent year for Southern California, which was seeing its fourth ruler (nominally, at least) in as many months. In June a group of filibustering frontiersmen, inflamed by rumors of incipient hostilities, had captured the northern town of Sonoma and claimed the entire territory in the name of the so-called Bear Flag Republic. In July, with war officially declared, regular American naval forces landed at Monterey and made short work of subduing the territory’s ten thousand or so Mexican civilians. “We simply marched all over California, from Sonoma to San Diego, and raised the American flag without protest,” wrote a member of the expedition. “We tried to find an enemy, but could not.”

On August 13 the Americans occupied Los Angeles unopposed. Commodore Robert F. Stockton got on the locals’ good side right away by having his musicians give nightly concerts. As in most of California, the Angelenos’ attachment to their mother country was far from ardent, and after three trouble-free weeks Stockton decided it was safe to return to Monterey, leaving Capt. Archibald Gillespie in charge. That turned out to be a big mistake.

For reasons best known to himself, Gillespie felt a need to clamp down firmly on the nonexistent opposition. He banned public and private gatherings, enforced a curfew, searched houses, and arrested citizens. Even worse, he restricted sales of liquor. Townswomen protested by giving Gillespie a basket of peaches rolled in cactus spines, but he refused to soften his rule. Within weeks Gillespie had worn out his welcome and was facing an angry crowd on his doorstep. His men repulsed the initial riot, but the next day a much larger group of citizens, armed this time, lay siege to their quarters.

A few hundred more troops and some matériel would have greatly strengthened the rebels, who were equipped with smoothbore muskets, homemade gunpowder, and improvised willow lances. But Mexico had little interest in contesting control of California. Its hands were full at home, where the city of Monterrey had just fallen to Gen. Zachary Taylor. The Californio guerrillas made do with their inadequate weapons, which they sometimes supplemented by dragging Americans from their mounts with lassos. They also relied on expert horsemanship, as well as ruses like herding wild horses back and forth in the distance to give the impression of a large cavalry force.

Soon after Gillespie’s garrison was surrounded, though, a daring former trapper named “Lean John” Brown rode north through enemy territory (jumping a thirteen-foot ravine at one point, running twenty-seven miles after his horse dropped dead, and covering more than five hundred miles in less than six days) to bring word to Commodore Stockton. Eventually American forces commanded by Stockton, Maj. John C. Frémont, and Gen. Stephen W. Kearny