Manifest Destiny:
Mexican-American
War
Manifest Destiny Defined
 First coined by newspaper editor, John O’Sullivan in 1845.
".... the right of our manifest destiny to over spread and to possess the whole of the continent
which Providence has given us for the development of the great experiment of liberty and
federaltive development of self-government entrusted to us. It is right such as that of the tree to
the space of air and the earth suitable for the full expansion of its principle and destiny of
growth."
 Ideological basis for belief:
– Sincere belief in democracy and republicanism
– Idealized view of U.S. as model for others
 Ideology intertwined with racist and imperialistic
ideas about Indians and Mexicans.
Reasons for Manifest Destiny
 Americans tempted by “free” land
– U.S. stopped at Mississippi
– Knew of California and Oregon
 Develop trade with Far East
– Pacific Coast to Far East – need base
– Jealous of Mexico’s success
 Fear of Foreign Invasion
– British Claims to Oregon; Mexico in south
Examples of Early U.S. Ideology
 Louisiana Purchase and Lewis & Clark Exploration
 Florida and the Seminole War - 1818
– Jackson “conquers” territory from Spain




Adams-Onis Treaty – 1819
Texas Revolution
New Mexico and the Santa Fe Trail
Oregon: 1818 - agreed with Britain to leave it “Free
and open”, but by 1840s U.S. changes policy
The Spanish Settle Texas
The original inhabitants were Native Americans, living
in Texas for thousands of years.
The Spanish explorers were the first Europeans to
visit Texas, crossing it several times during the
1500s. Spain claimed Texas based on these
explorations. Finding little wealth in the region, they
made no attempt to settle.
In 1689, the Spanish discovered the ruins of a
French fort built on the coast that had been
destroyed by local Indians. Alarmed that the French
would try to claim the land, the Spanish came up
with a plan to settle Texas.
The Spanish Settle Texas
The mission system
 The Spanish attempted to
settle Texas by building
missions, small settlements
designed to convert the
Indians to Christianity.
 The Spanish had effectively
used the mission system in
Mexico.
 They built two dozen missions
and presidios between the late
1600s and 1700s; they also
built
San
Antonio
and
Nacogdoches.
 Despite Spanish hopes, the
missions failed and the towns
never flourished.
The mission system ends
 Native Americans rejected
mission life, where they were
expected to give up their
culture as well as their
religion.
 Some Indian groups viewed the
Spanish
as
dangerous
trespassers, attacking the
missions and towns.
 The system was built to
convert the Indians and to
thwart French claims. In 1762,
France ceded to Spain much of
its land claim in North
America.
 By 1800, Spain still claimed
Texas, but had only three
settlements in the region.
Americans Move into Texas
 Moses Austin
– In 1820, Austin proposed to Spanish colonial officials that, in
exchange for land, he would build a colony in Texas. The Spanish
agreed, but Austin died before he could start. His son, Stephen
F. Austin, would carry out his wish for a colony. By 1824, about
300 families lived on farms and ranches throughout Austin’s
colony.
 Mexican independence and the empresarios
– Mexico gained its independence in 1821. The new government
wanted Texas settled. They assigned large amounts of land to
empresarios, contractors who recruited settlers and established
colonies. Austin was the most successful of the empresarios.
– By 1830, Texas had more than a dozen colonies with 30,000
settlers. This included several thousand enslaved Africans and
4,000 Tejanos, or Texans of Mexican heritage.
The Texas Revolution
American settlers in Texas had to agree to certain conditions
in exchange for receiving land. They had to surrender their
American citizenship; swear allegiance to Mexico; adopt the
Roman Catholic religion; and hold the land for seven years.
The settlers ignored the Mexican rules. They kept bringing
in slaves, even after Mexico outlawed slavery. Settlers were
still Americans, not Mexican. In 1830, Mexico passed a law
halting American immigration and sent troops to Texas to
enforce it.
Mexican officials suspected that the U.S. wanted to acquire
Texas. Originally claimed as part of the Louisiana Purchase,
the U.S. had dropped its claim. But when an offer was made
to buy a large part of Texas for $1 million, Mexicans refused,
but their fears of U.S. intentions were confirmed.
From the Alamo to Independence
Rebel Texan forces captured San Antonio, which contained a
fort called the Alamo. Santa Anna led an army into Texas to
punish the rebels and put down the unrest once and for all.
On February 23, 1836, Santa Anna’s force of 6,000 soldiers
reached San Antonio. A demand of surrender was met with
cannon fire from William Travis. The Mexican army laid
siege to the fort, pounding it for 12 days and nights. The
fort was finally stormed, with nearly all defenders killed.
While the Alamo was under siege, a small group of Texans
met at Washington-on-the-Brazos to issue the Texas
Declaration of Independence. They wrote a constitution for
the new, independent nation.
Fighting for Independence
The Runaway Scrape
 Santa Anna’s army continued
to defeat the Texan rebels.
Prisoners were held in the
presidio at Goliad.
 After
Mexican
soldiers
executed 340 prisoners at
Goliad, Houston retreated to
the east with his poorly
trained army.
 Word of Houston’s retreat and
the news of the Goliad
Massacre started a panic.
 In what would be called the
Runaway Scrape, thousands of
Texans,
including
many
Tejanos, fled Santa Anna’s
advancing army.
Texans victorious
 Santa Anna’s army followed
Houston’s forces to San
Jacinto,
where
Houston
managed to take the Mexican
army by surprise. Texans
shouted,
“Remember
the
Alamo!”
and
“Remember
Goliad!” as they won a quick
victory.
 The captured Santa Anna was
forced to sign the Treaties of
Velasco, ending the war.
Mexico had to withdraw its
troops and recognize Texas
independence.
 Problems
with
Mexico
continued for the Republic of
Texas.
Texas Independence
 March 1, 1836, declared Independence
– Elected Sam Houston as President
 Under duress, Santa Ana signs Treaty of
Velasco
 Mexican government repudiated treaty and
never recognized Texas Independence
U.S. Annexation of Texas
 Houston and Texas immediately ask for
annexation by U.S.
 Northern liberals oppose because they fear
spread of slavery.
 Texas remains independent nation until
March 1, 1845.
 Mexico sees annexation as a declaration of
War and diplomatically leaves Washington
The Annexation of Texas
Proponents
 Americans who believed in
Manifest Destiny wanted to
admit Texas to the Union.
 Supporters
viewed
the
Texas Revolution in the
spirit of the American
Revolution.
 Southerners
supported
annexation because Texas
allowed slavery, and its
admission would boost the
South’s political power.
Opponents
 Americans were concerned
that the U.S. would have to
bear the substantial Texas
debt.
 Northerners
opposed
annexation because it would
spread slavery westward
and increase slave states’
voting power in Congress.
 A major argument in
Congress was that the
Constitution said nothing
about
admitting
an
independent nation.
Factors leading to MexicanAmerican War
 Mexican anger over annexation of Texas
 Dispute over Texas/Mexican border
– Nueces River or Rio Grande
 Instability of Mexican government
– 19 governments in 25 years
 Polk Administration’s drive to expand U.S.
– Polk saw his mandate as creating a coast-tocoast nation
The Annexation of Texas
 A Republic for nine years
– The annexation question was a significant issue in the
1844 presidential election. When James K. Polk, the
pro-annexation candidate, won, Mexico warned that it
would consider the annexation of Texas as a declaration
of war.
 Tyler signs the joint resolution
– Outgoing
president John Tyler signed the joint
resolution of Congress into law just three days before
the end of his term, in March 1845.
 Texas becomes a state
– Voters in Texas overwhelmingly approved annexation,
and Texas became a part of the United States on
December 29, 1845.
Tensions between the United States and Mexico
Mexico
responds
The annexation of Texas enraged the Mexican
government. Mexico had refused to recognize the
Republic of Texas, and they broke off diplomatic ties
with the U.S. after the vote for annexation.
Polk and
Manifest
Destiny
In March 1845, James K. Polk became president. He
wanted the nation to acquire the land between Texas
and the Pacific Ocean. These sparsely populated
territories, New Mexico and California, belonged to
Mexico. Polk sought an opportunity to acquire these
remote regions.
The
boundary
dispute
The U.S. needed to secure the boundary between
Texas and Mexico. Texans put the border at the Rio
Grande. Mexico maintained it was at the Nueces River.
There were also disputes about money, and Polk wanted
these issues resolved.
Diplomatic Prelude to War
 1845 Polk sends Zachary Taylor to Corpus
Christi. Encamped on Nueces River
 Sends John Slidell to negotiate. He offers:
– $5 million for New Mexico west of Rio Grande
– $25 million for California
 Strong anti-U.S. sentiment meant that Mexico
would not accept offer
 March 1846 Taylor crossed Nueces and war
begins.
The Mexican-American War
The war
starts
While Slidell was in Mexico, Polk ordered General
Zachary Taylor to take his troops into the disputed
border territory. The U.S. used the event of a minor
skirmish to declare war on Mexico.
Fighting
the war
American forces under Taylor advanced into northern
Mexico. General Winfield Scott marched his forces
into Mexico City. In a matter of months, U.S. forces
had captured New Mexico and California. When their
capital fell, the Mexican government was forced to give
in.
Results of
the war
The Treaty of Guadalupe Hidalgo (1848) forced
Mexico to turn over a huge tract of land known as the
Mexican Cession, while the U.S. paid Mexico $15
million. Debate continues over whether the MexicanAmerican War was justified.
Treaty of Guadalupe Hidalgo
 Annexed half of Mexico to the U.S. (San
Antonio)
 Created Rio Grande as international border
 U.S. Paid $15 million to Mexico for territory.
 1848 irony - Mexicans hear of Gold Rush in
California and Treaty on same day.
 In 1854, Gadsden Purchase solidifies southern
boundary and mineral deposits to U.S.
Aftermath of Battle
 If it was the United States’ manifest destiny
to conquer land, were they also to conquer
people?
 Three barriers to the “All Mexico” plan
– Northern liberals hated conquest
– Slavery question
– Racism – could the U.S. really incorporate all
the 8 million Mexican and Indians?