Everything Everywhere Daily: The Mexican-American War

In the February 25, 2025 episode of Everything Everywhere Daily, host Gary Arndt delves into the often-overlooked yet pivotal conflict in North American history—the Mexican-American War. This comprehensive episode uncovers the war’s origins, key battles, influential figures, and lasting impacts on the geopolitical landscape of the United States and Mexico.

Introduction: A Forgotten Conflict

Gary Arndt opens the episode by highlighting the Mexican-American War's relative obscurity despite its profound significance. Declared by the United States Congress on May 13, 1846, the two-year conflict fundamentally reshaped the map of North America. Arndt emphasizes, “The Mexican American War is one that has largely been forgotten” (00:25), setting the stage for an in-depth exploration of its causes and consequences.

Causes of the War: Manifest Destiny and Territorial Ambitions

The roots of the Mexican-American War are deeply embedded in the United States' westward expansion and the ideology of Manifest Destiny—the belief that the U.S. was destined to stretch from the Atlantic to the Pacific Ocean. Arndt explains, “Many Americans believed that they had a manifest destiny to eventually control everything from the Atlantic to the Pacific” (02:15). This expansionist zeal was fueled by the Louisiana Purchase of 1803, which nearly doubled the country’s size and intensified migration westward.

The annexation of Texas was a critical flashpoint. After declaring independence from Mexico in 1836, Texas sought admission to the Union, which Congress approved on March 1, 1845. Mexico, viewing Texas as a rebellious province, responded by withdrawing its diplomats from the United States. A major dispute arose over the southern border of Texas: the United States claimed the Rio Grande river, while Mexico asserted it was the Nueces River further north (05:45). This border disagreement was a direct catalyst for war.

Diplomatic Failures and the Path to War

President James Polk, a staunch advocate of westward expansion, played a pivotal role in escalating tensions. In November 1845, Polk dispatched John Slidell to negotiate the purchase of California for up to $25 million. However, Mexico’s refusal to engage with Slidell effectively ended diplomatic efforts, pushing both nations closer to conflict (09:10).

The Outbreak of Hostilities: The Thornton Affair

In early 1846, U.S. troops under General Zachary Taylor entered the disputed territory between the Nueces River and the Rio Grande. On April 25, 1846, a Mexican force attacked a patrol led by Captain Seth Thornton, resulting in the death or capture of all 80 American soldiers. Arndt identifies this skirmish, known as the Thornton Affair, as the immediate spark for war, noting, “President Polk used this skirmish...as justification for war” (13:30).

Early Victories and Congressional Declaration

Following the Thornton Affair, U.S. forces swiftly secured victories at the Battle of Palo Alto on May 8 and the Battle of Resaca de la Palma on May 9, both near the Rio Grande. These successes bolstered American morale and led Congress to declare war on Mexico on May 13, 1846. Despite these victories, Arndt points out that support for the war was not unanimous, particularly among Northern Americans who viewed it as an unjust expansionist venture. Prominent figures like Abraham Lincoln and Henry David Thoreau vocally opposed the war, arguing that the United States should not engage in the same imperialistic actions that characterized European powers (18:20).

Major Campaigns and Battles

The Bear Flag Revolt and California Campaign

In June 1846, the Bear Flag Revolt erupted in California, led by William Ide and John Fremont. American settlers declared California an independent republic, symbolized by a makeshift flag featuring a bear and a star. Although the rebellion was short-lived, US Naval forces swiftly took control of Monterey and San Francisco by July, incorporating California into US territory (23:50).

Stephen Kearney’s Peaceful Annexation of New Mexico

Simultaneously, General Stephen Kearney advanced into Santa Fe, New Mexico, in August 1846. Without significant resistance from Mexican Governor Manuel Armijo, Kearney declared New Mexico a U.S. territory, establishing a military government that ensured a smooth and bloodless annexation (27:35).

The Battle of Buena Vista

One of the war’s most significant engagements occurred on February 22-23, 1847, at the Battle of Buena Vista. General Zachary Taylor’s 5,000 troops confronted General Antonio Lopez de Santa Anna’s 15,000 Mexican soldiers. Utilizing superior artillery, strategic defensive positioning, and tactical maneuvers, Taylor repelled multiple Mexican assaults. In a memorable moment, when Santa Anna demanded Taylor’s surrender, Taylor famously retorted, “Tell him to go to hell” (33:10). This decisive victory cemented Taylor’s status as a national hero and marked the last major Mexican offensive of the war.

Winfield Scott’s March to Mexico City

General Winfield Scott launched an amphibious assault on Veracruz on March 9, 1847, swiftly capturing the city. He then embarked on a methodical march to Mexico City, winning key battles at Cerro Gordo in April, Contreras and Churubusco in August, and Chapultepec in September. By September 14, 1847, U.S. troops had entered Mexico City, signaling the impending end of the war (42:50).

Disparities in Military Strength and Mexican Challenges

Arndt underscores the asymmetry between the two nations. The United States had a population three times larger than Mexico's and a more robust economy. Additionally, American forces were better equipped and more professionally trained. In contrast, the Mexican army was plagued by disorganization and political instability, having changed presidents nine times in two years. Ulysses S. Grant, who served as an assistant quartermaster during the war, described the Mexican forces as “hardly an organization” with poorly treated soldiers and ineffective leadership (38:00).

The Treaty of Guadalupe Hidalgo: War’s Conclusion and Aftermath

With the U.S. forces occupying Mexico City, the momentum shifted towards negotiation. The Treaty of Guadalupe Hidalgo was signed on February 2, 1848, officially ending the war. Under the treaty, Mexico ceded over half a million square miles of territory, including present-day California, Arizona, New Mexico, Utah, Nevada, and parts of Colorado and Wyoming. The Rio Grande was established as the official border between the United States and Mexico, resolving the Texas boundary dispute. In exchange, the United States paid Mexico $15 million and assumed $3.25 million in debts owed to American citizens (50:40).

Five years later, in 1853, the Gadsden Purchase further adjusted the border by acquiring 29,670 square miles of southern Arizona and southwestern New Mexico for $10 million. This acquisition facilitated the construction of a southern transcontinental railroad and resolved remaining border disputes (54:30).

Legacy: Shaping Modern North America

Despite its significant impact, the Mexican-American War is often overshadowed by the American Civil War that followed less than a decade later. Arndt notes, “a simple look at the map will tell you that it was the Mexican American War… which has shaped the map of North America today” (57:15). The territorial gains from the war laid the foundation for the United States’ emergence as a continental power and set the stage for future conflicts over expansion and statehood.

Conclusion: Lessons from History

Gary Arndt concludes by reflecting on the war’s enduring legacy, emphasizing the profound and lasting changes it wrought on both nations. The Mexican-American War not only redrew borders but also influenced the cultural and political dynamics of the United States and Mexico, effects that are still evident in contemporary geopolitics and societal structures.

Notable Quotes

• Gary Arndt on Manifest Destiny: “Many Americans believed that they had a manifest destiny to eventually control everything from the Atlantic to the Pacific.” (02:15)

• John Slidell’s Mission: The failed diplomatic attempt to purchase California for $25 million, as orchestrated by President Polk, set the stage for inevitable conflict. (09:10)

• Zachary Taylor’s Defiance: In response to Santa Anna’s demand for surrender at the Battle of Buena Vista, Taylor famously declared, “Tell him to go to hell.” (33:10)

• Ulysses S. Grant on the Mexican Army: “The Mexican army of that day was hardly an organization. The private soldier was picked from the lower class of the inhabitants.” (38:00)

Final Thoughts

The episode expertly weaves together historical facts and narratives, providing listeners with a nuanced understanding of the Mexican-American War. By shedding light on this crucial but forgotten conflict, Gary Arndt underscores the importance of remembering and learning from history to comprehend the present geopolitical realities of North America.

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