It was during this cruise that Bartlett achieved his greatest professional fame. The Mexican–American War broke out during this cruise. Commodore
John D. Sloat claimed California for the United States on July 7, 1846, and Commander
John B. Montgomery of USS
Portsmouth arrived at the coastal village of
Yerba Buena on July 9, 1846 to take control of the area for the United States. As Lieutenant Bartlett was a fluent speaker of Spanish, and was well read in legal matters, he was detailed by Commander Montgomery on August 14, 1846, to represent the military government as
alcalde at Yerba Buena, in a position functionally similar to the office of
prefect in the Mexican system. In one of his last acts as alcalde, Bartlett formally changed the name of Yerba Buena on January 30, 1847 to that by which it is known today: San Francisco. Bartlett resigned the office and rejoined the
Portsmouth when the ship received new orders and left the area. Bartlett, as an experienced surveyor, also ordered the creation of some of the first maps of the city-to-be.
Montgomery Street, still a prominent thoroughfare in San Francisco, was named for his commanding officer, and although Bartlett Street is most probably named for him, some say it was for
Washington Montgomery Bartlett, who was the twentieth
mayor of San Francisco, and later the sixteenth
governor of California. ==Pacific Coast Survey==