Explain the Impact of the Mexican War up to 1861

I. Background information on Mexican War
A. Happened due to Mexico's stubbornness to sell California and America's annexation of Texas, 1845.
B. The Mexican War started on April 25, 1846 when American troops led by General Zachary Taylor crossed the Nueces River to the Rio Grande.
1. Mexican soldiers attacked and killed or wounded 16 soldiers.
2. The war was also called Polk's war because he sent soldiers to Texas and inadvertently crossed the Nueces River.
C. The Americans then launched on a campaign that led through Mexico and finished at Mexico City.
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