Mexican War 1846-1848

The Mexican-American War (1846-48)

Overview

The Mexican-American War was a pivotal conflict in U.S. history, fueled by expansionist desires and manifest destiny. It lasted from 1846 to 1848 and was characterized by significant military engagements and territorial transformations.

Maps of the United States

• Map 1: United States (1840-1842)Depicts U.S. territory before Texas annexation, showing key locations such as Maine, Oregon Country, and political boundaries.

• Map 2: United States (1845-1846)Represents U.S. territory prior to the Mexican-American War, prominently including Texas, which was a point of contention between the U.S. and Mexico.

• Map 3: United States (1850)Illustrates the territorial changes after the Mexican-American War, highlighting newly formed states and adjusted boundaries, which included California and New Mexico.

Causes of the Mexican War

• Manifest DestinyThe belief that it was America’s God-given right to expand westward, reflecting a mindset that justified territorial acquisition. This concept was visually depicted in John Gast's painting "American Progress" (1872), symbolizing the idea of American superiority and the notion of civilizing the West.

• Texas AnnexationThe U.S. annexed Texas in 1845, which raised tensions with Mexico. The annexation was driven by financial and military issues facing Texas and the desire for statehood. Texas officially became the 28th state in December 1845, prompting Mexico to sever diplomatic ties with the United States and stoking fears of further U.S. territorial expansion.

• Boundary DisputeThere was a significant disagreement over Texas's southern border, with the U.S. claiming the Rio Grande as the boundary and Mexico insisting on the Nueces River. This dispute was critical in escalating tensions that led to the war.

Election of 1844

• Political ContextThe election saw James K. Polk (Democrat) defeat Henry Clay (Whig), largely due to Clay's lack of support for the annexation of Texas, which alienated many voters, particularly abolitionists. Polk’s victory was also aided by strong support in key regions like New York, where a small number of votes made a considerable difference.

President Polk's Agenda

• Polk was known for his hardworking and ambitious program accomplished within a single term:

  • Lowered tariffs, enhancing trade conditions.

  • Restored the independent treasury in 1846 to stabilize the economy.

  • Resolved the Oregon Territory dispute with Britain in 1846, ensuring U.S. claim to the region.

  • Pursued California acquisition, facing significant diplomatic reluctance from Mexico, which ultimately led to military conflict.

Steps to War

1. Disputed Border (June 1845):Polk ordered U.S. troops to the contested areas along the Texas border to establish military presence.

2. Diplomatic Efforts:John Slidell was sent to negotiate the purchase of California and New Mexico for $30 million; however, Mexico refused to engage in negotiations.

3. Military Engagement (March-April 1846):U.S. troops camped at the Rio Grande and clashed with Mexican forces, which escalated into full-blown conflict.

4. Declaration of War (May 1846):Polk reported that American blood had been shed on American soil, which galvanized Congress to declare war on Mexico.

Support and Opposition to the War

• Support:The war was supported by many Americans who saw territorial expansion as a sign of national pride. Southern states were particularly supportive, anticipating the addition of slave states.

• Opposition:Many northern abolitionists opposed the war, fearing the expansion of slavery into newly acquired territories. Abraham Lincoln's "Spot Resolutions" critically questioned the justification for the war, seeking clarity on the events that led to American troops engaging Mexican forces.

Key Military Events and Geography

• An array of maps illustrate U.S. troop movements across varied geography during the conflict, detailing significant battles such as Palo Alto, Resaca de la Palma, and the Siege of Veracruz.

Treaty of Guadalupe Hidalgo (1848)

• Provisions of the TreatyThe treaty, forced upon Mexican President Santa Anna, was critical in concluding the war. It established the Rio Grande as Texas's southern border and significantly expanded U.S. territory, including California, Nevada, Utah, as well as parts of Arizona, New Mexico, Colorado, and Wyoming. In exchange, the U.S. paid Mexico $15 million and assumed debts owed to U.S. citizens.

Northern Opposition to the Treaty

• The treaty faced backlash from Northern Whigs who opposed the war and feared it would lead to the expansion of slavery. During 1847, there were threats to cut war funding, highlighting the deepening sectional divide regarding slavery and territorial expansion. Ultimately, the treaty was approved through a series of political compromises.

Reflection Prompt

• A discussion on the role of the federal government in exacerbating tensions between Northern and Southern states prior to the Civil War is crucial in understanding the long-term impact of the Mexican-American War on American political and social dynamics.

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