Chapter 10
Section 2: The
Mexican War &
Slavery Extension
Annexation of Texas
• 1836- Texas voted to be annexed by
the US
–Protect themselves from Mexico
• Debate
–South & Democrats wanted itslave state?
–North & Whigs opposed- shift the
balance of power
• Worried it would lead to a war
with Mexico
• John Tyler signed a treaty of
annexation with Texas in April
1844
–June- Whigs controlled Senate
defeated the treaty
–Feb. 1845 Congress approved
the treaty
• December 1845- Texas became
the 28th state
War with Mexico
• March- Mexico broke off
diplomatic relations with the US
–Boundary dispute
• Polk wanted more than Texas
–Sent Ambassador John Slidell to
Mexico City with an offer to buy
NM & CA for $30 million
• Mexican government refused to
receive Slidell
• Polk sent 3,000 troops under
General Zachary Taylor into
southern Texas
–set up camp between the Rio
Grande & Nueces Rivers
–Mexico attacked
• Polk asked for a
declaration of
war
–Mexican war
was declared
on May 13,
1846
Bear Flag Revolt
• Group of settlers launched a
surprise attack on Sonoma &
proclaimed the Republic of CA
• Captain John Fremont helped the
rebels push the Mexican army out
of CA
• July 1846 US troops under
General Stephen Kearny crossing
into New Mexico
• Occupied Santa Fe by mid August
• Then marched to CA to join
Fremont
• Together defeated the Mexican
Army
Fighting in Mexico
• Taylor took the war into Mexico
• Battle of Buena Vista Feb. 1847
–Met Santa Anna & 20,000 troops
–US won & Santa Anna retreated
•Polk dispatched forces under
General Winfield Scott to
Mexico City
• March 1847- Scott captured
Veracruz, then marched to Mexico
City
–Defeated Santa Anna’s forces &
ended the war on September
14th
The Treaty of Guadalupe Hidalgo
• Signed on February 2, 1848
• Terms
–Mexico gave up its claim to
Texas & recognized the Rio
Grande as the border
–Mexico gave NM & CA to the US
• US paid Mexico $15 million
• US agreed to pay claim made by
American citizens against Mexico
• 1853 Mexican government sold
30,000 square miles of NM &
Arizona to US for $10 million
–Known as Gadsden Purchase
• Effects of the war
–Established boundaries of
continental US
–Left many Mexicans deeply bitter
towards the US & decades of poor
relations & misunderstanding
–Opened the doors for a large
wave of immigration
The Wilmot Proviso
• Brought the question of slavery into
politics
• Worried about the balance of
power
• Slavery not allowed in the new land
–Congress didn’t pass it
–Never became law