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Mexican War

1846 - 1848
  • Between the War for Independence and Operation Iraqi Freedom, the armed forces of the United States have participated in twenty-one principal wars and in numerous smaller conflicts and operations. In each of these American men and women have paid a high price for the nation's freedom, selflessly sacrificing life or limb for an honorable cause.

    Principal sources of information for the figures, explanatory text and illustrations appearing below include the National Archives and Records Administration; U.S. Navy Historical Center; Department of Defense; Department of Veterans Affairs; and The Oxford Companion to American Military History, from which all quotations are taken.

    Mexican War  (1846 - 1848)

    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 ServiceNumber ServingKilled in ActionOther DeathsNon-mortal Wounds
    Army 1,72111,5504,102
    Navy         1         3
    Marines       11       47
    Total    78,7171,73311,5504,152