Regular Army (United States) - Mexican-American War

Mexican-American War

At the start of the Mexican War, Congress tried to get along with just eight infantry regiments of Regulars, but gave the President power to expand their companies to one hundred enlisted men during the war. After hostilities commenced, Congress had to add nine new regiments with the same organization as the old ones to the Regular infantry. The cavalry of the U.S. Regular Army consisted of two light regiments trained to fight mounted or dismounted and designated as dragoons. Although raised as Regulars, the nine new infantry regiments created during the Mexican War were disbanded when the war was over. By contrast to the army of mainly militiamen who fought the War of 1812, in the Mexican War, one of every ten soldiers was a militiaman, three were Regulars and six were war volunteers. During the Mexican War, some 73,260 volunteers enlisted, although fewer than 30,000 actually served in Mexico.

Congress added two new regiments to the Regular Army in 1855 because of the need to protect the large additional territory obtained from Mexico.