Westward Expansion and the Mexican-American War Unit 6, Lesson 1

Essential Idea The ideal of “Manifest Destiny” inspired Americans to claim the West, which led to the Mexican-American War.

Manifest Destiny Manifest Destiny: Manifest Destiny—the idea that Americans had a God-given right to conquer and civilize North America This idea encouraged settlers to move west before, during, and after the Civil War

Overland Trails These settlers, called “overlanders,” used routes like the Oregon Trail Manifest Destiny

Moving West Reasons for Migration: 1. Economic—some went west for mining, ranching, and farming “Mountain men” trapped fur and served as guides to settlers 2. Religious—Mormons, led by Brigham Young, went west to escape religious persecution

Frontier Life Life on the Frontier: Over time, settlers did increasing damage to the environment As settler population grew, conflict with Native Americans increased Settlers dealt with isolation, loneliness, a rugged environment, and Native American attacks

Election of 1844 Election of 1844: James K. Polk, called the “expansion president,” ran against Henry Clay Polk’s platform: 1. Polk was committed to “manifest destiny” and expansion 2. Polk promised to annex Texas as a new state 3. Polk promised to acquire California 4. Polk would end sharing the Oregon Territory with England

“Fifty-four Forty or Fight!” Election Mandate? Polk won, showing that Americans wanted to expand the country Polk’s Accomplishments

Expansion Begins Texas: After Polk’s election, the United States annexed Texas Consequences: Annexing Texas angered anti-slavery northerners because it opened new land to slavery Annexing Texas infuriated Mexico, which felt Texas was really theirs Tension between the United States and Mexico rose

Oregon Treaty Oregon: “Fifty-four Forty or Fight!”—this slogan stated the desire of Americans to own ALL of the Oregon Territory up to the 54° 40’ latitude line However, Polk did not want war with both Mexico AND England Oregon Treaty—the United States agreed to split the Oregon Territory with England at the 49° line (not 54°40’) Consequences: War with England was avoided Northerners were upset that more land for future free states was not obtained, especially after Texas had been annexed Manifest Destiny and Oregon

The Mexican-American War: Causes 1. Annexing Texas Mexico never fully recognized Texas independence Many Mexicans felt that the United States had “stolen” Texas 2. Desire for California Polk offered to buy California (and New Mexico) from Mexico Mexico, angry, refused to even negotiate, raising tension

The Mexican-American War: Causes 3. Texas Border Dispute Mexico said the Texas/Mexico border started at the Nueces River, the United States said it started at the Rio Grande River Both countries claimed the land between these two borders

The Spark of War Ignited War Ignites: Polk ordered troops to march into the disputed territory The Mexican army attacked and killed 11 of the soldiers Polk claimed American blood was shed on American soil Congress declared war on Mexico

Opposition to War Opposition to War with Mexico: Many northerners and abolitionists opposed the war as a conspiracy to create new future slave states Wilmot Proviso: Wilmot Proviso—to appease northerners, this suggested making all land won from Mexico FREE Pro-slavery congressmen made sure the Wilmot Proviso never passed

The Mexican-American War: The Strategy Part 1: Capture Santa Fe in New Mexico What Happened: Santa Fe was a trade center for northern Mexico Capturing it cut much of northern Mexico from its southern capital, Mexico City

The Mexican American War: The Strategy Part 2: Capture California What Happened: “Bear Flag Revolt”—California, like Texas, was fighting for independence from Mexico American troops helped free California Mexico lost control of its northern half

The Mexican-American War: The Strategy Part 3: Invade from North What Happened: Troops crossed the Rio Grande and invaded south toward Mexico City Mexican troops left Mexico City unguarded to intercept American troops

The Mexican-American War: The Strategy Part 4: Capture Mexico City What Happened: General Winfield Scott took troops and captured Mexico City With the northern half of Mexico gone and the capital captured, Mexico had to surrender

The Mexican-American War Ends Terms of Peace: Treaty of Guadalupe Hidalgo—in this peace treaty, sold its northern half to the United States and recognized the Rio Grande as the Texas border Polk and Expansion (Watch first 2:40) Mexican Cession—this land made up what is now the American Southwest