The Mexican-American War, a significant conflict that reshaped the map of North America, took place between April 1846 and February 1848. This pivotal war between the United States and Mexico was driven by expansionist ambitions and territorial disputes, ultimately resulting in the U.S. acquiring vast territories from Mexico. Understanding the Mexican American War Date is crucial to grasping the context and consequences of this historical event.
Key Dates and Timeline of the Mexican-American War
To fully comprehend the Mexican-American War date and its significance, it’s essential to examine the timeline of events leading up to, during, and immediately following the conflict.
Prelude to War (1845 – April 1846)
The seeds of the Mexican-American War were sown in the years preceding the official Mexican American War date of April 1846. Several factors contributed to the escalating tensions:
- 1845: U.S. Annexation of Texas: The Republic of Texas, which had previously declared independence from Mexico, was annexed by the United States in 1845. Mexico, which still considered Texas as its territory, viewed this annexation as a hostile act and severed diplomatic relations with the U.S.
- September 1845: Slidell Mission: U.S. President James K. Polk, a strong proponent of westward expansion, sent John Slidell to Mexico City on a secret mission. Slidell’s objectives were to negotiate the disputed Texas border, settle financial claims from U.S. citizens against Mexico, and attempt to purchase the territories of New Mexico and California. However, the Mexican government, under President José Joaquín Herrera, refused to even receive Slidell, perceiving his mission as an attempt to dismember their nation.
- January 1846: Occupation of Disputed Territory: Following the snub of Slidell, President Polk ordered troops under General Zachary Taylor to advance and occupy the region between the Nueces River and the Rio Grande. This area was claimed by both nations, with Mexico considering the Nueces River as the southern border of Texas, while the U.S. claimed the Rio Grande as the boundary. This move was a deliberate provocation, setting the stage for armed conflict and directly leading to the Mexican American War date.
War Declared and Key Battles (May 1846 – September 1847)
The official start of the Mexican American War date is marked by the U.S. declaration of war in May 1846, following a skirmish in the disputed territory:
- April 25, 1846: Thornton Affair: Mexican troops crossed the Rio Grande and clashed with U.S. soldiers under Captain Seth Thornton, resulting in American casualties. This event provided President Polk with the justification he needed to declare war.
- May 9-13, 1846: Polk’s War Message and Declaration of War: President Polk, already preparing a war message based on Mexico’s refusal to negotiate and settle claims, swiftly revised it upon receiving news of the Thornton Affair. On May 11, he addressed Congress, stating that Mexico had “invaded our territory and shed American blood on American soil.” Congress overwhelmingly approved a declaration of war on May 13, 1846, officially marking the Mexican American War date as the commencement of hostilities.
Mexican-American War: U.S. declaration of war
Alt text: U.S. declaration of war against Mexico, 1846, highlighting President Polk’s proclamation leaflet.
- Key Battles and Campaigns: The Mexican-American War saw a series of significant battles and military campaigns. Some of the most important include:
- Battle of Palo Alto (May 8, 1846) and Battle of Resaca de la Palma (May 9, 1846): Early U.S. victories under General Zachary Taylor in Texas.
- Battle of Buena Vista (February 22-23, 1847): Another major victory for Taylor, solidifying U.S. control in Northern Mexico.
- Veracruz Campaign (March 1847): General Winfield Scott launched an amphibious invasion of Veracruz, successfully capturing the city.
- Battle of Cerro Gordo (April 17-18, 1847): Scott’s forces decisively defeated Mexican troops, opening the path to Mexico City.
- Battles for Mexico City (August-September 1847): A series of battles including Contreras, Churubusco, Molino del Rey, and Chapultepec, culminating in the capture of Mexico City in September 1847.
James K. Polk
Alt text: Portrait of U.S. President James K. Polk, a key figure during the Mexican-American War period.
Treaty of Guadalupe Hidalgo and End of War (February 1848)
The Mexican American War date range concludes with the signing of the Treaty of Guadalupe Hidalgo:
- February 2, 1848: Treaty of Guadalupe Hidalgo: Negotiated by Nicholas Trist, the Treaty of Guadalupe Hidalgo was signed, officially ending the Mexican-American War. In this treaty, Mexico ceded a vast expanse of territory to the United States, including present-day California, Nevada, Utah, most of Arizona and New Mexico, and parts of Colorado, Kansas, Oklahoma, and Wyoming. In return, the U.S. paid Mexico $15 million and assumed claims of U.S. citizens against Mexico. The ratification of this treaty in February 1848 marks the definitive end date of the Mexican-American War.
Causes of the Mexican-American War
Understanding the Mexican American War date also requires acknowledging the underlying causes that led to the conflict. Beyond the immediate triggers, several long-term factors contributed to the war:
Texas Annexation
As previously mentioned, the annexation of Texas by the U.S. in 1845 was a primary catalyst. Mexico had never formally recognized Texas independence and viewed the annexation as an encroachment on its sovereignty.
Border Dispute
The disagreement over the Texas-Mexico border was another significant cause. While Texas claimed the Rio Grande as its southern boundary, Mexico insisted on the Nueces River, placing a considerable amount of territory in dispute. President Polk’s decision to station troops in the contested area was a deliberate escalation of this border dispute.
Manifest Destiny
The concept of “Manifest Destiny,” the belief that the United States was divinely ordained to expand its dominion across the North American continent, played a crucial ideological role. This expansionist ideology fueled American desires for westward territorial acquisition, including California and New Mexico, which Mexico possessed.
Opposition to the War in the U.S.
Despite widespread support for the war, especially in the South and West, there was significant opposition within the United States, highlighting the contentious nature of the conflict even as it occurred within the Mexican American War date timeframe.
Whig Opposition and Spot Resolutions
The Whig Party, the main political opposition to President Polk’s Democrats, largely opposed the war. They viewed it as an unjust and aggressive land grab. Whig Congressman Abraham Lincoln famously introduced the “Spot Resolutions,” challenging President Polk to specify the exact “spot” where American blood was shed on American soil, questioning the legitimacy of Polk’s justification for war.
Abraham Lincoln
Alt text: Early photograph of Abraham Lincoln, then a Congressman, who opposed the Mexican-American War.
Abolitionist Concerns and Civil Disobedience
Abolitionists also strongly condemned the war, fearing it was a Southern plot to expand slavery into new territories acquired from Mexico. Notable figures like Henry David Thoreau protested the war. Thoreau’s essay “Civil Disobedience” originated from his refusal to pay taxes in protest against the war, arguing against unjust government actions.
Soldier's Adieu
Alt text: Lithograph depicting public enthusiasm for the Mexican-American War contrasting with the underlying dissent.
Conclusion
The Mexican-American War, spanning from April 1846 to February 1848, was a transformative period in the history of both the United States and Mexico. Understanding the Mexican American War date is just the starting point. The war’s causes were complex, rooted in territorial disputes, expansionist ideologies, and political maneuvering. While the U.S. emerged victorious, gaining vast territories and solidifying its position as a continental power, the war also ignited domestic debates about slavery and the morality of expansionism. The Mexican American War date marks not just a period of armed conflict, but a turning point with lasting consequences for the geographical and political landscape of North America.
