Fight with Mexico for New Territory (College Board AP® US History)

Summary

Timeline

April 25, 1846: Mexico attacks U.S. troops near the Rio Grande, beginning the war

May 13, 1846: The United States Congress declares war on Mexico

May 9−8, 1846: Battle of Palo Alto and Battle of Resaca de la Palma

September 21-24, 1846: Battle of Monterrey

March 9, 1847: Siege of Veracruz

September 13−14, 1847: Battle of Chapultepec and fall of Mexico City

February 2, 1848: Treaty of Guadalupe Hidalgo signed, officially ending the war

The Mexican–American War (1846–48) began due to tensions over both Texan and US desires for more land, driven by Manifest Destiny. The settlement of the war decreased the size of Mexico by fifty per cent and expanded US territory significantly. With the addition of new territory, once owned by Mexico, a new ethnic group, Hispanic, was added to the country’s population. Hispanics made major contributions to the United States over the following decades and centuries.

Causes and Effects of the Mexican–American War

Causes of the Mexican–American War

• The main causes of the Mexican-American War were the annexation of Texas and failed negotiations with Mexico

Annexation of Texas

• Settlers in Texas wanted to join the United States after gaining independence from Mexico

• The annexation of Texas took place in 1845

• Texas remained a republic for nine years before being annexed

  • This was because the issue of slavery had to be resolved before it could enter the Union

• Texas would enter the Union as a slave state  

Failed negotiations with Mexico

• In 1845, John Slidell was sent to Mexico to:

  • purchase California for the US

  • negotiate the Texas–Mexico border dispute

• The US claimed the border to be at the Rio Grande River

• Mexico claimed the border to be at the Nueces River

• Mexico would not agree to either proposal, increasing tensions

Source:
https://upload.wikimedia.org/wikipedia/commons/b/b4/United_States_1848-02-1848-05.png

The Mexican–American War (1846–48)

• The Mexican-American War was between Mexico and the United States

• The war was driven by:

  • disputed over territory

  • the desire of the United States for westward expansion under the ideas of Manifest Destiny

Key battles and events

• Disputed territory conflict:

  • General Zachary Taylor fought Mexican forces in the disputed territory between the Rio Grande and Nueces Rivers

    • He defeated Mexican forces at Palo Alto (May 8, 1846) and Resaca de la Palma (May 9, 1846)

    • Taylor’s victory at the Battle of Monterrey (September 1846) solidified US control over northern Mexico

• The capture of Mexico City 

  • General Winfield Scott led a successful campaign, landing at Veracruz (March 1847) and capturing the fortress

  • His troops advanced inland, leading to the Battle of Chapultepec (September 1847) and the fall of Mexico City

• The Treaty of Guadalupe Hidalgo (1848) 

  • This treaty ended the war and established key territorial and political agreements

• Territorial gains:

  • The United States acquired 525,000 square miles of land, including present-day California, Nevada, New Mexico, and parts of Arizona and Colorado (Mexican Cession 1848)

  • The U.S. paid Mexico $15 million for this land

  • The border between the nations was established at the Rio Grande River

  • Impact on population:

    • Mexican citizens received U.S. citizenship but suffered voter discrimination, segregation, and lack of educational opportunities

    • Indigenous peoples in the region had no rights, worsening their marginalization