Entering the Military Academy in 1838, James Longstreet graduated
and was transferred to the Fourth U.S. Infantry with the brevet rank
of second lieutenant in July of 1842. He was transferred to the Eighth
Infantry in 1845 and promoted to second lieutenant. With the Eighth
Infantry, he was part of the military occupation of Texas (1845 - '46)
and later served in the war with Mexico.

During the Mexican war, the future Confederate general was engaged
in the battles of Palo Alto, Resaca de la Palma, Monterrey, the siege
of Vera Cruz, the battle of Cerro Gordo, the capture of San Antonio,
the battles of Contreras, Churubusco, Molino del Rey, and the
storming of Chapultepec, where he was severely wounded.

Longstreet was promoted to first lieutenant in February of 1847, and
was given the brevet rank of captain in August of 1847, for gallant
and meritorious conduct in the battles of Contreras and Churubusco.
One month later he was given the brevet rank of Major for gallant and
meritorious conduct in the battle of Molino del Rey.

He was Regimental Adjutant (Eighth Infantry) between 1847 and 1849.
He was promoted to Captain in 1852. In July of 1858, he was given the
position of Major-Staff-Paymaster. Taking a leave of absence early in
1861, he later, in June, resigned his commission in the Army of the
United States and joined the Confederate Army. Raising to the rank of Lieutenant General, James Longstreet is considered,
by some, to have been the finest corps commander in the Army of Northern Virginia.