Accepted by the United States Army in August 1846, the 1st Regiment of New York Volunteers was transported around Cape Horn to California, where it served as garrisons in Yerba Buena, Monterey, Santa Barbara, Los Angeles and San Diego.
Elements of the Volunteers under Lieutenant Colonel Henry Stanton Burton were involved in operations of the Pacific Coast Campaign in Baja California, captured and garrisoned towns there, fighting in the Battle of La Paz, Siege of La Paz and defeated local forces at the Skirmish of Todos Santos after the peace was negotiated in 1848.
Arriving in San Francisco 19 March 1847, companies D, E, G, and I were transported by store-ship to the California Capital Monterey.
From this post, companies of the regiment were deployed by ship to lower California where they participated in the battles of La Paz, and the final Skirmish of Todos Santos.
It is said of Co. D "This Company was without doubt the last command of American troops to leave the soil of Mexico after the close of the Mexican War.