The American Mexican War
Taylor Presidency
• William Henry Harrison
– Shortest Presidential Term = One Month
– Caught pneumonia during inauguration speech
• John Tyler Became President
– Not a Whig
• Didn’t uphold Harrison’s policies or positions
• Protective Tariffs, national bank, or internal improvements
• Entire cabinet resigned in protest (Webster Exception
– Became a man without a party
• Democrats considered a traitor
– Left democrats over Jackson stance on Nullification
• Whigs felt betrayed
– Didn’t nominate him in next election
Western Expansion
• John L. O’Sullivan
– Newspaper Editor
– Coined term “Manifest Destiny”
• God wanted us to spread from coast to coast
• Moral Justification for expansion
• West was populated by Mexicans and Native Americans
– “Our manifest destiny is to overspread the
continent allotted by Providence for the free
development of our yearly multiplying millions”
• Oregon and California
– Fertile Land
• Western Plains
– Ranch land and Gold
Annexing Texas
• Mexico encouraged American immigration
into the southwest and Texas (then part of
Mexico)
– Wanted to generated grow of area
– Opposed Slavery
• Mexicans = Catholics
• American Immigrants = Slave Holders
• Conflict Developed
– Outlawed Immigration – Americans still flowed into territory
– 1835 – 30,000 Americans in Texas
• Called for Annexation and Statehood
• Texans rebelled against the Spanish dictator Santa Anna
Texas War for Independence
• The Alamo
– February 23, 1836 – Santa Anna demanded Alamo
surrender
• Battle and Siege lasted 12 Days
• Mexican Casualties = 1,544
• American Casualties = around 1/10th of Mexican
– Santa Anna ordered wounded to death
• Alamo encouraged
– Texans to further rebel
• Gained support of sympathetic Americans
• Sam Houston – Leader of Texans
– Captured Santa Anna
• Bought freedom by signing treaty that recognized
independence of Texas
• Mexican congress never agreed, but ended war
Annexation
• The Lone Star Republic
– Constitution adopted slavery and outlawed free
blacks
– Sam Houston First President
– Voted for annexation to the United States
• Jackson delayed
– Feared debate between anti and pro slavery factions could
hurt Van Buren Election
– Or start a war with Mexico
– Immigration to Texas increased
• 150,000 by 1845
– Texas and American Citizens wanted
– Congress did not because of sectional debate
Election of 1844
• Whigs
– Nominated Henry Clay for president
• No mention of slavery or Texas Annexation
– Fear it would cause Civil War
• Felt Calhoun was using Texas issues to cause sectional rift
• Democrats
– Nominated James Polk for President
• Expansionist – Platform reflected position
• Favored by Jackson and other who wanted Texas annexed
• Southerners and Slave holders obsessed with Texas
• Polk won a narrow victory
– Liberty Party (Anti-Slavery) took enough votes way
from Clay to give Polk victory
President Polk
• The New Jacksonians
– Emphasized Slaveholding Democrats
– Expansionist
• Polk
– Chief concern expansion of United States
• Tyler last act was to Annex Texas
– Knew would be Polk’s first official business, gave into pressure
– Mexico sent troops to the boarder of Texas in protest
• Vowed to acquire Oregon and California by any possible
means
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Oregon Territory held jointly with Britain
Expansionist wanted war to gain territory
Britain gave up territory, US gained Oregon And Washington
California still Mexican Territory
The Mexican War
• General Zachary Taylor
– Sent to antagonize Mexican forces at Rio Grand
– Polk wanted to engage war, but needed
congressional approval
• Military incident was needed to influence congress
– May 9, 1846 – Skirmish between US and Mexican
forces
• 11 Americans Kill
– Polk told congress of massacre, received
declaration of war
Opposition to War
• Whigs and Anti-Slavery advocates opposed War
• Whigs eventually change position
– See new land as way to expand territory
– Cannot win office if they don’t support expansionism
– Believed (Correctly) Polk exaggerated incident at the
Rio Grand
• Abraham Lincoln – Spot Resolution, called on Polk to name
the place with blood was spilled
– Believed war was attempt by pro-slavery forces to
expand US slave territory
• Anti-Slavery Society – war was “waged solely for the
detestable and horrible purpose of extending and
perpetuating Amerian slavery throughout the vast territory
of Mexico.”
– Northern Intellectuals and Northern Religious leaders
opposed the war
Military Buildup
• Thomas Heart Benton (Senator from Missouri)
– Polk wanted, “a small war, just large enough to require
a treaty of peace, and not large enough to make
military reputations, dangerous for the presidency”.
• The Army was ill prepared to fight a war with
Mexico
– Most troops were southern volunteers eager to fight
and expand slavery
– Men were “impressed” or lied to by recruiters to fill
required regiment numbers
– Undisciplined forces engage in plunder, rape, and
murder
• The media ran untrue/scrupulous stories about Mexicans
• As conditions grew worse, soldiers became hard to control
Battle for California
• John C. Fremont
– Champion of American Settlement in California
– Knows as “The Pathfinder”, he mapped the Oregon
Trail
• His reports glorified California and Oregon and encourage
American immigration to the west coast
– When war broke out with Mexico, he led troops to
liberate California
• Repelled the weak Mexican forces and established “The Bear
Flag Republic”
• US Navy landed and declared California part of US Territory
• Polk’s expansionist plans taking root
– New Mexico was easily taken by Colonel Stephen Kearny
General Zachary Taylor
• Early success in battle created great fame for
Taylor
– Polk immensely jealous of Taylors popularity with
the press and public
– Rumors that Taylor will be next Whig candidate for
president
• Polk’s war strategy flawed
– Believed Taylors army could live off land
– Returned Santa Anna to Power in Mexico
– Promoted General Winfield Scott Commander
• Taylor, ignored demotion, and attacked Mexican Forces
– Increased popularity
– Forced Polk to reappoint him
Liberation of Mexico City
• September 13, 1847
– Scott entered Mexico City
– Forced Mexico to seek peace
– Santa Anna Resigned
• February 2, 1848
– Treaty of Guadalupe Hidalgo signed
• Mexico gave up all claims to Texas and established Rio
Grand as boarder
• Mexico ceded New Mexico and California
• US paid Mexico $15 Million for territory
– Whig Intelligencer – “We take nothing by conquest… Thank
god.”
Aftermath
• 17 month long war
– US Casualties
• Wounded = 4,152
• Died in Battle = 1,733
• Died of Disease = 11,550
– Army ill prepared for tropical/desert war in Mexico
– Sanitation conditions of the army were very bad
• Acquired almost 1,000,000 square miles of
territory
– Texas, New Mexico, California, Arizona, and Nevada
– Made US a true transnational country
– Gadsden Purchase of 1853
• Completed modern map of the US
• US Paid $10 Million to Mexico for land no Arizona