Because Mexico never recognized the independent Republic of Texas after the Texas Revolution of 1836, annexation of Texas by the United States sparked a war between the two nations in 1846, especially after General Zachary Taylor's forces violated the Mexican border at the Nueces River where they skirmished with a detachment of the Mexican army. Mexico declared a "state of defensive war" with the United States, and the U.S. Congress followed with its own declaration against Mexico a few weeks later. The Polk administration launched a two-pronged attack--one sending U.S. soldiers westward to invade New Mexico and then California (aided by a naval squadron), and the other southward into the heart of Mexico. This latter aspect of the war required two major invasions before victorious American forces finally took Mexico City on 14 September 1848.

Although the Mexican army was far superior in number, the Americans were much better trained, equipped, and led. The 8,500 men in the regular U.S. Army were joined by more than 73,000 volunteers organized into dozens of state regiments. The agreement that settled the war, the Treaty of Guadalupe-Hidalgo, ceded to the U.S approximately one-third of Mexico's territory--lands that included California, New Mexico, Arizona, Nevada, Colorado and Utah, making the United States a truly continental nation.

American Casualties, Mexican War

Branch of Service	Number Serving	Killed in Action	Other Deaths	Non-mortal Wounds
Army		1,721	11,550	4,102
Navy		1		3
Marines		11		47
Total	78,717	1,733	11,550	4,152

 

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