4th US Infantry History during the Mexican War

The Fourth U.S. Infantry Regiment participated in many of the major battles of the Mexican War.
These included the May 8th and May 9th battles of Palo Alto, Texas and Resaca de la Palma,

Losses to the Fourth Infantry during the two days were 1 officer, 1 sergeant, and 3 privates killed and
2 officers and 6 privates wounded. 1 officer and 1 private later died from their injuries.

U. S. successes at the battles of Palo Alto and Resaca de la Palma also helped U. S. public opinion
turn more for the war. Also, the battles showed the merit of both a standing army and a professional
officers corps, trained at a formal military academy, both of which were previously questionable needs
in the eyes of the American public.

The next major battle in which the Fourth Infantry participated was Monterrey, Mexico. After the battle
the Regiment remained in the area of Monterrey.

In early 1847 the Regiment left the area of Monterrey and returned to Texas. In February, headquarters
and Companies A, B, C, D, and I left Palo Alto. On the 13th of February, all but company B boarded the
ship “North Carolina” and sailed for the Isle of Lobos, where they arrived on the 21st. Company B arrived
at the Isle of Lobos, aboard the ship “Henry” on the 22nd. Headquarters and companies A, C, D, E, and
I left the Isle of Lobos on March 2nd. They disembarked on March 9th and encamped 2 miles from Vera
Cruz, Mexico. Company B arrived later. Headquarters and those companies present (companies F, G, H,
and K being absent) participated in the siege of Vera Cruz, Mexico.

Several additional battles led up to the assault on Mexico City itself. Among these was the battle of
Churubusco in August of 1847 and the assault on El Molino Del Ray two weeks later. Located a few
miles from Mexico City, El Molino Del Ray was a mill. A storming party organized to assault the mill
included two officers and 100 men from the Fourth Infantry. In all, the storming party, which took the
mill at bayonet point, lost 11 of 14 officers. The remainder of the Fourth Infanty was part of the final
assault on El Mino Del Ray. In the assault the regiment lost, killed and wounded, 64 enlisted men and
3 officers.

Overall, one fourth of the entire American assault force was killed or wounded.

The assault on Mexico City started on September 12th with the storming of Chapultepec.

With the capture of Mexico City major campaigning came to an end. For several months the Fourth
Infantry was part of the garrison occupying the city. Over a period of time, units were withdrawn to
points along the Camino Real. Finally, in June of 1848, the regiment was assembled at Jalapa for return
to the United Sates.

The treaty of Guadalupe Hidalgo, signed in February and ratified in March of 1848 ended the war. The
treaty stipulated, in part, that Mexico was to give up the territory that makes up the current states of
California, Arizona, New Mexico, Texas, and parts of Colorado, Utah, and Nevada. In return they were
to receive fifteen million dollars, in compensation for war related damage.

The Mexican War gave the United States’ officer corps both a taste of the glory of war and a look at
what war was really like. In all, many future Civil War figures, both Union and Confederate, stood out.
These include Captain Robert E. Lee and Lieutenants Thomas (Stonewall) Jackson, Ulysses S. Grant,
George Picket, George McClellan, James Longstreet, and Richard Ewell.

In all, the regiment had 18 officers and 199 enlisted men killed or wounded.

During the Mexican War most soldiers were armed with either muzzle-loading rifles or muskets,
the latter being more common since they were quicker and easier to load.