[2] In late December, the former Californio military commander of Yerba Buena and a rancher from the San Mateo peninsula, Francisco Sanchez, imprisoned the American Mayor of Yerba Buena, Washington Bartlett, and five of his men, who were all engaged in a foraging raid on the peninsula.

After receiving the news of the abduction on December 29, Commodore Montgomery in San Francisco ordered Marine Captain Ward Marston to rescue Bartlett and his men.

[3] Six men of the U.S. sloop Warren, who had gone ashore to buy cattle from Mexicans for food, were taken hostage by a group under Francisco Sánchez.

[1] One of the hostages was Lieutenant Washington Allon Bartlett,[1] the alcalde of Yerba Buena (soon to be renamed San Francisco).

Captains Joseph Aram and Charles Maria Weber, commanding U.S. volunteers at Santa Clara and San Jose respectively, were sent to free them.