The War with Mexico

Miriam B. Murphy
The History Blazer, April 1995

When Americans elected James Polk as their eleventh president in 1844 they ushered in an era of expansionism and war that would soon reshape the nation. The new administration sailed along on a slogan coined by an editor in the summer of 1845, Manifest Destiny. Historian Bernard DeVoto called it “one of the most dynamic phrases ever minted, Manifest Destiny.” Before Polk’s term of office ended U.S. territory encompassed the former Republic of Texas; the “Oregon” country wrested from the British (“54-40′ or fight”), including present Oregon, Washington, Idaho, and parts of Wyoming and Montana; and a huge tract of former Mexican lands that included present California, Nevada, Utah, Arizona, New Mexico, and parts of Colorado and Wyoming.

Each acquisition was part of a complex web of international relations and political maneuvering. For Utahns the most important of these was the Mexican War–a conflict that a century and a half later remains outside the historical awareness of many Americans. As Gilberto Espinosa wrote in 1965, “The War with Mexico is a matter of history…but it should not continue to be ‘The War That Nobody Knows’; every American should know at least something about it.”

Obscure as it may be for some, the Mexican War nevertheless produced military heroes–including Zachary Taylor, Polk’s successor as president; a colorful, somewhat ragtag group of patriotic mercenaries–the Mormon Battalion, and a huge annexation of land by the United States.

A number of prominent Americans opposed Polk’s hawkish expansionism: Henry Clay, former president Martin Van Buren, Daniel Webster, and John C. Calhoun. But for Polk the prize to be obtained, especially from a confrontation with Mexico, was simply too tempting. He wanted California at all costs; and, of course, it would not do to have a foreign country in possession of the land between the eventual Golden State and the rest of the United States. Mexico must give it all up.

In 1845 Polk sent Taylor (Old Rough and Ready), a veteran of the War of 1812, the Black Hawk War, and the second Seminole War, with an army to the Rio Grande. After Taylor’s troops were attacked by Mexicans, Polk asked for and received a declaration of war on May 13, 1846.

A month and a half later Capt. James Allen appeared in the Mormon immigrant camp at Council Bluffs, Iowa, to recruit a battalion of men for the war. Mormon leaders hoped that sending a large body of their followers west at government expense would help the destitute Saints in their exodus. Indeed it did. The Mormon Battalion’s major contribution to their country came not from any military exploits but in forging a wagon route across the Southwest on one of the longest infantry marches undertaken by U.S. troops.

While the Mormon Battalion marched and their co-religionists continued toward the Great Basin, Zachary Taylor, Winfield Scott, and other military leaders pursued victory on the battlefield. At the Battle of Buena Vista, February 22–23, 1847, Taylor’s troops, outnumbered 4 to 1, defeated Santa Ana, making Taylor a national hero and a shoo-in for the U.S. presidency in 1848. By September 14, 1847, Mexico City had fallen to the Americans.

Peace negotiations between the two countries culminated with the Treaty of Guadalupe Hidalgo on February 2, 1848. It established the boundary between the two republics beginning at the mouth of the Rio Grande in the Gulf of Mexico westward, with several jogs, to the Pacific Ocean.

Thus, when the pioneer company of Mormons arrived in the Salt Lake Valley in July 1847 they entered territory claimed by Mexico, explored in the 18th century by Spanish and Mexican parties (including the Dominguez-Escalante Expedition), and linked with Spanish-speaking settlements via the Old Spanish Trail that cut through southern Utah. With no permanent Mexican or Spanish-speaking settlements in the area, however, it was easy for the Mormons to ignore Mexican claims to the land. The Saints were initially pleased to be beyond the authority of the U.S. government. But less than a year after the pioneers’ arrival in Utah, the Treaty of Guadalupe Hidalgo bound them securely to the U.S., first as a territory in 1850 and finally as the 45th state in 1896.

Historic forces continue to shape both the state and the nation. In the 20th century the immigration to Utah of thousands of Spanish-surnamed individuals and families has helped to diversify the state’s population, enrich its cultural heritage, and renew its historic association with Mexico and the Southwest.

See: Bernard DeVoto, The Year of Decision, 1846 (Boston, 1942); Nathan Covington Brooks, A Complete History of the Mexican War, 1846-1848 (Chicago, 1965); Charles S. Peterson et al., Mormon Battalion Trail Guide (Salt Lake City; Utah State Historical Society, 1972).