Manifest Destiny=War
with Mexico!!!
Vs.
Americans had shown their
support for Manifest Destiny,
and expansion, when they
elected James K. Polk
(Democrat) as president in
1844.
Polk’s two goals were
to annex (add)
Texas and acquire
Oregon.
James K. Polk
• In his election, Polk had talked of taking
over all of Oregon.
• “Fifty-four forty or fight!” was one of
his slogans. The parallel of 54, 40 N
latitude was the northern boundary of
the shared Oregon Country (between
the U.S. and Great Britain).
• Rather than fight for it, however, Polk
settled for half. In 1846, the U.S. and
GB agreed to divide Oregon at the 49th
parallel.
• Polk was smart to not fight over
Oregon, he had bigger problems with
Mexico.
• In 1845, Congress had admitted Texas
as a state. However, Mexico still
claimed Texas as its own. They viewed
the annexation of Texas as an act of
war.
• To make matters worse, Texas and
Mexico couldn’t agree on the official
border between them. Texas claimed
the Rio Grande, while Mexico insisted on
the Nueces River.
Area in Dispute
Nueces River
Rio Grande River
• Mexico said they would fight for their claim on
Texas. Hoping to solve this issue peacefully, Polk
sent John Slidell to Mexico to offer $25 million for
Texas, California, and New Mexico. Slidell was
unsuccessful.
• Polk then sent General Zachary Taylor to the
northern bank of the Rio Grande. Mexico viewed
this as an act of war, and moved an army into place
on the southern bank.
• On April 25, 1846, a Mexican cavalry unit crossed
the Rio Grande and ambushed an American patrol.
They killed/wounded 16 American soldiers.
• When Polk heard what happened, he
declared, “Mexico has invaded our
territory and shed American blood upon
American soil.” He asked Congress for a
declaration of war.
• Despite controversy over the
truthfulness of his statement,
Southerners and Westerners supported
the war because they saw it as an
opportunity to expand.
• Northerners opposed the war. They
saw it as a plot to add more slave
territory to the U.S.
• Defeating the Mexicans proved to be
difficult because their army was so
large.
• The Americans had an advantage in
their well trained officers.
• General Taylor moved into northern
Mexico and after a 2 day battle,
defeated Santa Anna and his troops.
• Winfield Scott led a force from the
Gulf of Mexico toward Mexico City.
Despite resistance, Scott captured the
capital in 1847 which effectively ended
the war.
• On February 2, 1848, the MexicanAmerican War ended with the signing of
the Treaty of Guadalupe Hidalgo.
• In this treaty, Mexico1. Recognized Texas as part of the U.S.
with a boundary at the Rio Grande.
2. Ceded (gave up) the Mexican Cession
which included the present day states
of California, Nevada, Utah, most of
Arizona, and parts of New Mexico,
Colorado, and Wyoming.
• In return for this land, the U.S. agreed to pay
Mexico $15 million and promised to protect
the Mexican citizens living in the areas of the
Mexican Cession.
• The last bit of territory added to the
continental United States was a small strip of
land across what is now southern New Mexico
and Arizona.
• The government wanted this land for a
transcontinental railroad. In 1853, Mexico
sold this land-called the Gadsden Purchase-to
the U.S. for $10 million.
The U.S. now extended from “sea
to shining sea.”