To the officers and men of the Dragoons, the outbreak of hostilities with Mexico was a relief from the tedium of post life. Trained in the art of war, they were eager to test their mettle. War came soon enough. Preparations for the invasion of Mexican territory at several points began.

General Kearny was placed in command of the "Army of the West," which consisted of Companies B, C, G, I, and K of the 1st Dragoons, two companies of Artillery, two of Infantry and nine companies of Missouri Volunteer Cavalry. The latter were independent, under the command of Col. Alexander W. Doniphan. General Kearny chose the Quartermaster at Fort Scott, Capt. Thomas Swords to be his Quartermaster for the expedition.

The immediate objective of this army was to capture Santa Fe and push on into Upper California. Kearny's advance met only token resistance and soon occupied Las Vegas and Santa Fe without conflict. Leaving Doniphan in Santa Fe, Kearny took up the march to California on September 25, 1846. By early December, Kearny had almost reached San Diego.

On December 6, his command met and was nearly decimated by a body of Mexican soldiers under Gen. Andres Pico at San Pasqual, about 40 miles from San Diego. In the engagement Kearny had 300 men, composed of Volunteers and Companies B and C of the 1st Dragoons. The enemy was charged by Capt. Abraham Johnston with the advance guard. Captain Johnston was shot fatally at the commencement of the action. Captain Moore pursued the retreating Mexicans but his horses were tiring. Seeing the lagging mounts, the Mexicans turned and charged with lances. Forced back, Moore was killed just before the final retreat. Lieutenant Hammond, two sergeants, two corporals and ten dragoons died also. The flagging mules of the rest of the men finally caught up with the battle and Kearny routed the enemy.

The price was high. In the action the Dragoons lost three officers: Capt. Benjamin Moore, who had arrived at Fort Scott with the first contingent of Dragoons and commanded until October, 1842; Capt. Abraham Johnston, a close friend of Swords and frequent visitor to Fort Scott; and Lt. Thomas C. Hammond, who was assigned to Fort Scott in 1843. Fourteen dragoons were killed and almost all with lance thrusts. General Kearny and two other officers were wounded in the engagement. By the end of December, General Kearny with Company C of the Dragoons had occupied Los Angeles.

Company A of the 1st Dragoons marched with General John E. Wool from Texas into northern Mexico. Wool joined General Taylor southwest of Monterrey, and dragoons played an important role in stopping the attack of General Santa Ana at the Battle of Buena Vista. Four former Fort Scott dragoon officers, Capt. William Eustis, Capt. James Carleton, 1st Lt. Richard Ewell, and 2nd Lt. Joseph Whittlesey participated in the battle. Ewell was brevetted in later battles. Lt. John Love, who kept the sawmill running at Fort Scott, also was brevetted for hi actions at Santa Cruz de Rosales.

Dragoons had distinguished themselves well during the war. The war over, headquarters remained at Fort Leavenworth during 1847, but most of the men were away. Companies A and E were with Taylor in Mexico; Company B was reorganized at Jefferson Barracks and sent to Albuquerque. En route the company was attacked by the Comanche Indians at Grand Prairie, Arkansas, and lost five men killed and six wounded. Company F escorted General Scott from Vera Cruz to Mexico City and was present at the battles in and around the city. Companies D and K, as well as F, saw service in Scott's line in Mexico; and it was not until 1848 that the three companies were returned to the United States. Company F was sent to Fort Scott.

The information for this section was taken from the Historic Furnishing Report for The Dragoon Barracks written by Sally Johnson Ketcham.