The Mormon Battalion Historic Site is a historic site in Old Town, San Diego, California, built in honor of the members of the Church of Jesus Christ of Latter-day Saints (LDS Church) who served in the United States Army's Mormon Battalion during the Mexican–American War of 1846–1848.

The new center was opened to the public on January 30, 2010[5][6] and dedicated by church apostle Jeffrey R. Holland on March 26, 2010.

In July of that year, 496 men, 36 women and 43 children left Council Bluffs, Iowa, to assist the war efforts in California.

335 men and four women continued on to San Diego, under the command of Lt. Philip St. George Cooke.

Left without their original purpose, the members of the battalion instead found work in helping to secure San Diego.