Pacific Coast campaign (Mexican–American War)
The objective of the campaign was to secure the Baja Peninsula of Mexico, and to blockade/capture west-coast ports of Mexico—especially Mazatlan, a major port-of-entry for imported supplies.
Samuel F. Dupont, commander of the second class sloop-of-war Cyane, was ordered to blockade San Blas (about 125 miles south of Mazatlan).
On September 2, 1846 the Cyane captured two Mexican vessels in the harbor then a landing party spiked 34 cannons in the port of San Blas.
[2] On December 24, 1846, Secretary of the Navy John Y. Mason ordered Stockton to impose an effective blockade on the west coast of Mexico.
The conquest and annexation of was confirmed with the signing of the Treaty of Cahuenga by US Army Lieutenant-Colonel John C. Frémont and Mexican General Andrés Pico on January 13, 1847.
The articles of capitulation granted, to residents of Baja California who accepted the terms, the rights of United States citizens, along with retention of their own officials and laws.
[citation needed] Fortunately for Kearny, the means to occupy Baja California Sur arrived at San Francisco, in March and April, in the form of the 1st Regiment of New York Volunteers.
On May 30, General Kearny sent U.S. Army Lieutenant Colonel Henry S. Burton, with Companies A and B of the New York Volunteers to La Paz on the storeship Lexington.
[2] Meanwhile, to the north of La Paz, at Loreto and Mulege, local priest Gabriel Gonzalez Pereyra of Todos Santos and Padre Vicente Sotomayor of Comondú incited rancheros to join the resistance to the Americans.
In late September, Captain Manuel Pineda, of the Mexican army, arrived in Mulegé with officers and soldiers from Guaymas and began recruiting rancheros for his command.
Afterward, behind defensive works designed by Henry Wager Halleck defended by a 400-man garrison, the city remained in American hands for the rest of the war, with only a few minor skirmishes with Mexican forces nearby.
Meanwhile, in Baja California Sur, on November 16, the Mexican resistance forces under Pineda descended on La Paz, attacking the American garrison and pro-American locals, but were repulsed.
On January 11, 1848, a landing party from the bark USS Whiton"' under Lieutenant Frederick Chatard, captured the coastal fort of San Blas and brought off two pieces of artillery and two schooners, one belonging to the custom-house.
A week later, on January 18, Lieutenant Chatard landed a small party at Manzanillo and spiked three large guns defending the port, rendering it defenseless.
