The Mormon Battalion Historical Site is a visitor center in San Diego. The Mormon Battalion was the only religiously based unit in US military history, and it served from July 1846 to July 1847 during the Mexican-American War. The battalion was a volunteer unit of about 534-559 Latter-day Saints men. During its service, the battalion made a grueling march nearly 2,000 miles long from Council Bluffs, Iowa, to San Diego. At the site is exhibits and a 40 minute free tour.