The Mexican-American War

Summary

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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Everything Everywhere Daily continues to deliver rich, engaging content tailored for intellectually curious individuals. For more insightful episodes covering diverse topics from history to science, subscribe to the podcast wherever you get your podcasts.

Transcript

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After several years of rising tensions, on May 13, 1846, the United States Congress declared war on the nation of Mexico. The war only lasted two years and the conduct of the war was decidedly one sided. The conclusion of the war, however, resulted in changes to both countries which can still be seen on the map and felt on the ground today. Yet, despite being one of the most important conflicts in the history of North America, it's been largely forgotten. Learn more about the Mexican American War, its causes and its resolution on this episode of Everything Everywhere Daily. This episode is sponsored by Expedition Unknown. The Expedition Unknown podcast is back for another season. Did you know that 900 manuscripts were found near the Dead Sea containing the earliest known copies of the Old Testament? Or that in 1959 a group of hikers died under mysterious circumstances which became known as the Datlov Pass Incident? On the Expedition Unknown podcast from Discovery, Josh Gates travels the world to investigate history's greatest unsolved mysteries. He'll take you to the coast of Florida to chase the long lost treasure of Jose Gaspar through California to trace the flight path of A World War II pilot, Gertrude Tompkins, who disappeared and was never seen again and to Lake Huron to find the final resting place of the Griffin, the very first ship to explore the Great Lakes. Travel the globe with Josh Gates as he investigates some of humanity's greatest feats and most iconic legends. Listen to Expedition Unknown wherever you get your podcasts. This episode is sponsored by the Upfirst Podcast. Breaking news is broken. You're constantly doom scrolling on Facebook, Twitter or TikTok to get the latest updates so you don't miss anything. If this sounds like you, I recommend that you listen to the UpFirst podcast by NPR. NPR's UpFirst provides the top three news stories to start your day with digestible 10 to 15 minute episodes. It's all the news you need so you can get back to your life feeling informed while preserving your sanity. Letting you get ready, make breakfast or go to work. From politics to economics and both national and international news, upfirst is the go to daily habit for the news consumer who wants to stay informed but is forever strapped for time. With Upfirst you can start your day a little more in the know than you were when you went to sleep. Up first is the cure you need for your news fatigue. It lets you stay informed of the top stories while allowing you to spend the rest of your day on things more productive or more enjoyable. Listen now to the up first podcast from npr. The Mexican American War is one that has largely Been forgotten. Most people might know that there was such a war, but they would be hard pressed to tell you the reasons for the war or anything specific about it. If you roll back the tape of history, it seems almost inevitable that the United States and Mexico would eventually have some sort of conflict. The United States became independent from Britain in 1776. Mexico became independent from Spain in 1821. After independence, the United States began moving westward. The Louisiana Purchase in 1803 almost doubled the size of the country. More people began moving further west in search of land. Many Americans believed that they had a manifest destiny to eventually control everything from the Atlantic to the Pacific. The land that was part of Mexico in the early 19th century was land that had been claimed by Spain centuries earlier. The core of Mexico and the vast majority of the population and economy were located in the south, Far from the regions that today we call Texas, California, in the American southwest. This region had a very light presence by Mexico, given its distance from the capital, Mexico City. As migrants began moving into this region, they mostly came from the east and were English speaking, not Spanish speaking. Due to geography, they found it much easier to trade with the Americans to the east rather than the Mexicans to the south. The settlers in Texas and here I'll refer you to my episode on the history of Texas Declared independence from Mexico in 1836, something which was not recognized by Mexico, who treated Texas as a rebellious province. The event that really started the United States and Mexico down the path to war was the vote by Congress to annex Texas and admitted to the Union on March 1, 1845. In response to the vote, the Mexicans removed their diplomats from the United States. One of the major issues was that Texas had said that their southern border was the Rio Grande river, and Mexico said that it was the Nueces river further north. On March 4, President James Polk took office, who was a big advocate of Texas joining the Union and of the United States spreading westward. In November 1845, Polk sent an envoy, John Slidell, to Mexico to meet with the Mexican government. His mission was to make an offer to purchase California, which was another outstanding issue between the two countries. He was told to offer a maximum of $25 million to purchase California. However, the Mexican government refused to meet with him. In early 1846, US troops under General Zachary Taylor moved into the disputed region between the Nueces river and the Rio Grande. In order to solidify its claim to the area, President Polk sent a smaller force of 80 men to south Texas, just north of what is today Brownsville. Led by Captain Seth Thornton. On April 25, 1846, a Mexican force attacked the patrol led by Captain Thornton, killing or capturing all of the soldiers. Polk used this skirmish, known as the Thornton Affair, as justification for war. In many ways, this is exactly what President Polk was waiting for. They could now claim that they were attacked and that Mexico started the war. Zachary Taylor's forces defeated the Mexican army near the Rio Grande at the Battle of Palo Alto on May 8 and then at the Battle of Resaca de la Palma on May 9. On May 13, Congress declared war on Mexico with President Polk claiming that American blood has been shed on American soil. Support for the war was not universal. There was a significant faction of Americans who were against going to war, especially in the North. The likes of Abraham Lincoln and Henry David Thoreau opposed the war as an unjust expansionist conflict. They figured that if the United States was born of revolution, then they shouldn't be doing the exact same thing that the European powers did. The Bear Flag Revolt was an uprising by American settlers in California against Mexican rule. In June of 1846, during the early stages of the war, inspired by the expansionist beliefs of Manifest Destiny and tensions over Mexico's control over the region, a group of settlers led by William Ide and John Fremont seized the town of Sonoma on June 14, 1846. They declared California an independent republic and raised a makeshift flag featuring a bear and a star, hence the name the Bear Flag Revolt. However, the rebellion was short lived as US Naval forces took control of Monterey and San Francisco in July of 1846, officially placing California under US military rule. The Bear Flag Republic lasted only a few weeks before California was absorbed into a US territory. In August 1846, General Stephen Kearney led the army of the west into Santa Fe, New Mexico. Facing no resistance, as Mexican Governor Manuel Armijo fled without a fight. Kearney peacefully took control of the city, declared New Mexico a U.S. territory and establish a military government, ensuring a swift and bloodless annexation. By this time, just a few months into the war, the United States had taken most of what it wanted. It demanded a surrender from Mexico so they could negotiate terms, but Mexico refused. So the decision was made by the US to push further into Mexico. With that decision, US forces under General Zachary Taylor advanced into northern Mexico. The Battle of Monterey took place from September 20th to September 24th, 1846. The City of Monterey, a heavily fortified position defended by General Pedro de Ampudia, was strategically important for controlling northern Mexico. The US launched a three day assault facing fierce resistance from Mexican troops entrenched in strong defensive positions, including forts and barricaded streets. After intense urban combat, Taylor's forces, aided by artillery and flanking maneuvers, gained control of key positions, forcing Ampudia to negotiate a capitulation. Taylor agreed to an eight week armistice allowing the Mexican army to withdraw, a decision criticized by President Polk, who wanted an immediate push further into Mexico. The war up to this point was a string of American victories and there was a good reason for that. The United States had a huge advantage in almost every metric. Its population was three times that of Mexico's and its economy was even larger. Despite this advantage in resources, however, the Americans were actually outnumbered in almost every battle. Moreover, they had more modern weapons compared to the Mexican army, which used decades old firearms. The Mexican army was also nowhere near the level of the U.S. army in terms of professionalism. Ulysses S. Grant, who served as an assistant quartermaster in the war, later wrote the following in his the Mexican army of that day was hardly an organization. The private soldier was picked from the lower class of the inhabitants. When wanted, his consent was not asked. He was poorly clothed, worse fed and seldom paid. He was turned adrift when no longer wanted. The officers of the lower grades were but little superior to the men. The Mexicans also had another huge problem, political turmoil. During the two year span of the war, they switched presidents nine times. Many of them were more concerned with consolidating their own power than they were with fighting the United States. The Battle of Buena vista occurred on February 22 and 23, 1847 in northern Mexico, where General Zachary Taylor and his 5,000 US troops faced off against General Antonio Lopez de Santa Anna and his 15,000 Mexican soldiers. General Taylor's forces used superior artillery, defensive positioning in a narrow mountain pass and tactical maneuvering to repel multiple Mexican assaults. Santa Anna, believing he had weakened the US Line, demanded Taylor surrender. But Taylor famously responded, tell him to go to hell. After intense fighting, the Mexican army suffered heavy losses and short on supplies, retreated, allowing Taylor to claim victory. The battle cemented Taylor's reputation as a national hero and helped propel him to the US Presidency while also marking the last major Mexican offensive of the war. About two weeks later, on March 9, 1847, General Winfield Scott led an amphibious landing at Vera Cruz. He took the city immediately and then began to march towards Mexico City, following roughly the same route that Hernan cortes took over 300 years earlier. Scott gradually made his way towards Mexico City, fighting with the Mexicans, who fought defensive battles to slow him down. He won battles at Cerro Gordo in April. Contreras and Churubusco in August and Chaputepec in September. On September 14, 1847, U.S. troops entered Mexico City, effectively ending the war because the Mexicans didn't pursue terms earlier. Once the Americans were in Mexico City, they had very little leverage. Their only option now was a guerrilla war, which they had a difficult time doing considering the internal divisions within Mexico. The Americans had never intended to go so far into Mexico when the war started. But now there was talk of annexing all all of Mexico, considering that they were occupying most of it. Oddly enough, while it was mostly Northerners who initially objected to the war, it was Southerners who objected to the annexation of Mexico. They were concerned that Mexico, which had mostly an indigenous population, would skew the racial balance in the United States. Both sides now had an incentive to come to the negotiating table. The Americans didn't want to be occupying Mexico any longer as it tied up their troops. And too many Americans objected to the United being an occupying force. The Mexicans realized it was the only way to get rid of the Americans. They also accepted the reality on the ground. Their territories in the north were lost. Texas had been gone for over a decade at this point, and California had its own rebellion and now was occupied. Much of the rest of the territory was desert and too far away from the Mexican population centers in the south to defend and manage adequately. The end result was the Treaty of Guadalupe Hidalgo signed on February 2, 1848, which officially ended the Mexican American War and resulted in a massive territorial transfer to the United States. Guadalupe Hidalgo was a community just north of Mexico City and today is a neighborhood of Mexico City. Under the treaty, Mexico ceded over half a million square miles of land, including California, Arizona, New Mexico, Utah, Nevada, as well as parts of Colorado and Wyoming. In what became known as the Mexican Session, the Rio Grande was established as the official U. S. Mexico border, resolving the Texas boundary dispute. In exchange, the U.S. paid Mexico $15 million and agreed to assume $3.25 million in debts owed by Mexico to American citizens. Had Mexico at least met with John Slidell three years earlier, they may have wound up in basically the same place, but $7 million richer and without having gone to war and having been occupied. And this wasn't the end of territorial concessions. Just five years later, in 1853, U.S. ambassador to Mexico James Gadsden negotiated a land deal between the United States and Mexico in which the United States bought 29,670 square miles of territory in present day southern Arizona and southwestern New Mexico for $10 million. The purchase aimed to facilitate the construction of a southern transcontinental railroad and resolve lingering border disputes after the Mexican American War. Despite the importance of the Mexican American War, most people have forgotten it simply because it was overshadowed by the much larger civil war that came less than a decade later. Yet a simple look at the map will tell you that it was the Mexican American War, probably more than anything else, which has shaped the map of North America today. The executive producer of Everything Everywhere Daily is Charles Daniel. The associate producers are Austin Okun and Cameron Kiefer. Today's review comes from listener 2012 Road King Classic over on Apple Podcasts in the United States. They write Love love love it. I love this podcast. The variety of topics coupled with the proper attention to detail without the host's inclusion of personal opinion is both welcomed and reflect refreshing. Keep up the great work. Gary. As the newest member of the Completionist Club in North Carolina, I found the clubhouse in need of refreshments, so I filled the fridge with our local favorites, cheer wine, Sundrop, and plenty of barbecue. Nothing could be finer than to be in Carolina unless you're a Panthers fan. Well, thanks Road King. I'd like to formally welcome you to the Completionist Club, and it's always nice to see Tar Heels representing. As for the Panthers, well, you always have college basketball. Remember, if you leave a review or send me a boostogram, you too can have it read on the show.