Main content
Course: US history > Unit 5
Lesson 1: Sectional tension in the 1850s- The slave economy
- Life for enslaved men and women
- Early abolition
- The Mexican-American War
- The Compromise of 1850
- Abolition, slavery, and the Compromise of 1850
- Uncle Tom's Cabin - influence of the Fugitive Slave Act
- Uncle Tom's Cabin - reception and significance
- Uncle Tom's Cabin - plot and analysis
- The Kansas-Nebraska Act and party realignment
- Bleeding Kansas
- Manifest Destiny: causes and effects of westward expansion
- Sectional conflict: Regional differences
- Dred Scott v. Sandford
- Dred Scott, the Lincoln-Douglas debates, and the election of 1860
- The eve of the Civil War
© 2024 Khan AcademyTerms of usePrivacy PolicyCookie Notice
The Mexican-American War
The Mexican-American War, sparked by Texas annexation and Manifest Destiny, led to the U.S. gaining over a million square miles of territory. This war transformed lives, shifted national boundaries, and stirred political realignment. Despite its significant impact, it's often overshadowed in American memory by other wars.
Want to join the conversation?
- How much is 15 million dollars worth now?(12 votes)
- $15,000,000 in 1848 is worth $525,168,987.34 today(15 votes)
- What happened to the Mexican citizens who stayed in the conquered land(8 votes)
- They became American citizens. Second class ones (because they weren't white), but citizens nonetheless.(11 votes)
- What was the main reason that the war started?(4 votes)
- Greed. The White Americans were greedy for the lands and resources that belonged to their neighbor, so they broke in and stole one third of Mexico.(10 votes)
- What were the few causes of the war?(5 votes)
- Look up a list of The Seven Deadly Sins" (it's not a particularly Christian list... it goes back to Greek Philosophy). Now, consider that list in terms of how it might effect the affairs of neighboring nations. I'm sure that at least 4 or 5 things on that list can be applied as "reasons for the Mexican-American war". It will be up to you, as a moral philosopher, to assign the "sin" to which (or both) side.(4 votes)
- Why did they sign the papers?(3 votes)
- The Americans had sacked the capitol. This is how most conflicts and conquests had ended for centuries. Those incapable of defending territory lost territory. The victors often enslaved or killed the vanquished. As humanity has developed, these practices became unpalatable mostly in the 19th century and spearheaded by the English, but it is worth noting how they are judged by modern morality.(5 votes)
- In short, the Mexican-American War was caused because of the United States' repeated encroachment on Mexican territory, such as its' annexation of Texas, which Mexico refused to recognize as being independent. Therefore, Mexico also refused to recognize the claimed border between the two nations(5 votes)
- Was slavery in Mexico abolished by the Guerrero decree (which was never enacted into law) or legislation in 1837? Also, wasn't Texas cessation partly or maybe mostly driven by the significant decrees by the new Mexican president to consolidate power from the Mexican states to the central Mexican government, including the desolation of state legislatures and effectively abolishing the preceding Mexican constitution? Thank You(5 votes)
- why did so many people believe in manifest destiny?(3 votes)
- The belief justified their greed, their racism, and their need for self-approval.(4 votes)
- The MexicanAmerican War was caused because of the United States' repeated encroachment on Mexican territory.(4 votes)
- 6:40was this a common style of clothing back then?(4 votes)
Video transcript
- [Kim] This is a painting of US general Winfield Scott entering Mexico City on
September 15th, 1847. Scott landed with a US naval
fleet several weeks beforehand. He bombarded the coastal
stronghold of Veracruz and then fought his way
inland toward the capital. Scott actually followed the same route that Spanish conquistador
Hernan Cortes took more than 300 years earlier. Winfield Scott's campaign to Mexico City was just one of three fronts in the two-year-long,
continent-spanning effort of the United States to take
Mexican territory by force. The other two fronts were in
California and New Mexico. After the two nations made peace by signing the Treaty of
Guadalupe Hidalgo in mid 1848, the United States gained
over a million square miles of new territory, a landmass larger than
the Louisiana Purchase. For Mexico, this war was
a catastrophic defeat, which resulted in the loss of
about 1/3 of its total area. The Mexican-American War
doesn't really loom large in American memory, compared
to the Revolutionary War or the Civil War, but it
was a transformative event in the history of the United
States and North America. On the scale of national politics, the war led to political realignment, and eventually, the Civil War. But on a human scale, it
led to transformations in the lives of people
who lived in the West who went to bed one day in Mexico and woke up the next day
in the United States. National boundaries
shifted under their feet. For those people, the outcome
of the war meant new laws, customs, new friends and enemies, and even the loss of
rights and privileges. So let's dive a little deeper
into the causes and effects of the Mexican-American War. The war began in April of 1846. A Mexican cavalry brigade
attacked US forces who were under the command
of General Zachary Taylor across the Rio Grande River from the town of Matamoros, Mexico. After this attack, President James K. Polk sent a war message to Congress. He fumed that the Mexican
troops had invaded our territory and shed American blood on American soil. Now back up a minute. You may be wondering, as many keen observers did at the time, what exactly were US forces doing there near Rio Grande River in the first place? And the answer to that
reveals the two major causes of the war, Texas annexation
and Manifest Destiny. Let's start by talking
about Texas annexation. American settlers, many
of whom were slave owners, had been moving to Texas since the 1820s, when the region was still
controlled by Spain. After Mexican independence,
the country outlawed slavery. But the American settlers resisted the Mexican government's authority. In 1836, they rebelled and
won independence for Texas. They requested the United
States annex the new nation shortly thereafter, but
adding another slave state to the Union was politically dangerous for the administration at that time. So Texas remained an
independent nation until 1845. In 1845, Democratic president
James K. Polk took office. Now Polk was an ardent expansionist. He was a believer in Manifest Destiny, this idea that God
wanted the United States to expand across the
North American continent. Polk wanted to annex Texas, which his administration
undertook immediately. He also desperately wanted California, which was a hub of commerce
on the Pacific Ocean. This is actually before
gold was discovered there. So Polk sent a representative
to the Mexican government offering to buy California. But Mexico said California
was not for sale. Now Polk was determined
to get this territory with blood or money. So he came up with an alternate plan. The border between Mexico
and Texas was under dispute. So Polk directed General Zachary Taylor to go down into this disputed territory and provoke hostilities. And that's exactly what happened when the Mexican cavalry
attacked Taylor's forces. As far as Mexico was concerned, Taylor's troops were
invading their country, and they had no choice but to defend it. Despite Polk's war message saying that American blood had been
shed on American soil, many US politicians were
also skeptical about who started the war and where. A young Whig congressman from
Illinois named Abraham Lincoln demanded that Polk show him the exact spot where American blood had been shed. The war that ensued was
longer, costlier, and deadlier than the US government had estimated, which is often the case with wars. At its conclusion, Polk
had achieved his vision for Manifest Destiny. In the Treaty of Guadalupe
Hidalgo, which ended the war, the United States agreed
to pay Mexico $15 million, and in exchange, Mexico
ceded Texas, California, and most of the modern-day
Southwest to the United States. So what were the effects of this war? Well, the addition of this
Mexican cession territory had far-reaching consequences
for both the United States and the residents of the West. The existing resident of the territory, including Mexicans, Native Americans, and the descendants of Spanish colonists, found that life under the
rule of the United States could be very different than
under the rule of Mexico. Where Mexican law had abolished slavery and proscribed equality under the law for people regardless of color, the Texas constitution permitted slavery and denied civil rights
to non-white residents. For other residents of the territory, life didn't change much at all. Huge swathes of the West
were actually controlled by Native American nations,
like the Comanche Empire, which didn't care whether
the distant government who claimed their territory on paper was located in Mexico
City or in Washington DC. For the United States government, the addition of this new territory
was political kryptonite. Both Northerners and
Southerners were convinced that the opposite region was conspiring to limit their economic
opportunities in the West. During the war, Congressman
David Wilmot of Pennsylvania introduced a resolution in the House that would prohibit slavery in any territory gained from the conflict. The reaction to the Wilmot Priviso showed just how big the
sectional divide in the country was becoming, since party
lines broke down entirely. Northerners, Whig, and Democrat alike voted for the Wilmot Proviso, and Southerners, Whig, and
Democrat alike voted against it. Ultimately, the proviso
passed in the House was defeated in the Senate. And then gold was
discovered in California, just before the end of the war, sending hordes of prospectors West and making statehood for
California an urgent issue that would soon upset the balance of power between free and slave states in Congress. In other words, we can draw a direct line from the Mexican War to the breakdown of the
second party system, which was replaced by a solidly
Southern Democratic party and a new Northern Republican party, and from there to the Civil War.