In July 1846, Henry David Thoreau was arrested for tax delinquency and spent the night in jail. Thoreau had stopped paying his taxes in protest against slavery. When the United States purposefully created an incident that gave President Polk an excuse to declare war on Mexico, Thoreau declared the war to be immoral, and wrote his famous essay, “Civil Disobedience.” Towards the end of the war, Thoreau’s friend and mentor Ralph Waldo Emerson wrote, “The United States will conquer Mexico, but it will be as the man swallows the arsenic, which brings him down in turn. Mexico will poison us.”

Although there was great enthusiasm for the Mexican War in Southern and Western states, “President Polk’s War” was seen in the North as an intolerable expansion of slavery states. Only one regiment was successfully recruited in New England, and it was woefully undermanned when it reached Mexico.

In April 1847, the Massachusetts legislation passed resolutions charging that the war “was unconstitutionally commenced by the order of the President . . . with the triple object of extending slavery, of strengthening the slave power, and of obtaining the control of the Free States. On Dec. 19. James K. Polk accompanied by his then Secretary of State James Buchanan visited Boston, Ipswich, Lowell, Newburyport and other Massachusetts towns, making speeches but gaining little or no support for his expansionist plans.

Among those who opposed the war was former president John Quincy Adams of Quincy. future presidents Abraham Lincoln and Ulysses S. Grant, former vice-president John C.

On January 3, 1848, the House of Representatives passed a resolution stating that “the war was unnecessarily and unconstitutionally commenced by the president.”

Massachusetts Senator Daniel Webster, a Salisbury native, was viewed with suspicion as a leader of the “Cotton Whigs,” a faction of Northern Whigs that emphasized good relations with the South over anti-slavery policies. Their suspicions were confirmed when he supported the Compromise of 1850, in which the fugitive slave laws were strengthened.

Nearly 15.5% of the 90,000 U.S. soldiers in Mexico died, the highest rate of any foreign war in U.S. history. When Webster’s daughter Julia Webster Appleton learned that her brother Edward had died from typhoid fever in Mexico, she wrote, “I feel nothing but that my brother in the flower of his youth was a useless sacrifice—to what? —ambition & vainglory.”

Signing of the Treaty of Guadalupe Hidalgo in 1848 transferred the northern half of Mexico to U.S. control, and stopped Mexican resistance to U.S. annexation of Texas. This ended the era of Spanish and Mexican control, and in the succeeding years the remaining Hispanic and Native American populations were overrun by Anglo-American emigrants to the new frontier.

Sources:

• The Thoreau Reader The annotated works of Henry David Thoreau.
• Webster, Daniel. The Papers of Daniel Webster. Correspondence, Volume 6, 1844-1849. Hanover, New Hampshire: University Press of New England, 1984.
• Massachusetts Historical Society
• MassHistory.org