1. Manifest Destiny War With Mexico p. 362 - 368

2. Manifest Destiny and California Many Americans wanted to expand to the Pacific Ocean for trade with Asia and so the nation would be safely bordered by the sea instead of a foreign power. The U.S was willing to give $30 million for Mexico to accept the Rio Grande as the boundary and cede, or give up, California and West New Mexico, but Mexico refused. President Polk plotted to pull the Mexican provinces in the Union through war. He wanted to provoke Mexico into taking military action first. This way Polk could justify war to Congress.

3. Conflict Begins Mexicans did not recognize the Rio Grande as the boundary- Mexico insisted the boundary was the Nueces River. Polk used the dispute in Texas over the boundary line to help the war. President Polk ordered General Zachary Taylor to move his troops across the Nueces River to the Rio Grande. Mexican forces attacked a small force of Taylor’s soldiers. President Polk declared war on Mexico on May 13, 1846 because he declared that, “Mexico… shed American blood upon American soil.” Congress passed a declaration of war against Mexico.

5. American Attitudes Toward the War The American people were divided over the Mexican War. Northern abolitionist accused Democrats of waging the war to spread slavery.

6. Polk’s War Plan Polk had a three-part plan for the war with Mexico:  First, American troops would drive Mexican forces out of the disputed border region in Texas and make the border secure.  Second, the United States would seize New Mexico and California.  Finally, American forces would take Mexico City, the capital of Mexico. Americans captured New Mexico’s capital, Santa Fe, without firing a shot.

7. California and the Bear Flag Republic In June 1846, a small group of Americans had seized the town of Sonoma north of San Francisco and proclaimed it the independent Republic of California. They called the new country the Bear Flag Republic because their first flag showed a bear and a star on a white background. John C. Fremont declared that he would conquer California. This outraged many Californios, Mexicans who lived in Mexico. By January 1847, California was fully controlled by the United States.

9. The Capture of Mexico City With their victories in New Mexico and California, the Americans met their first two goals in the war. President Polk then launched the third part of his war plan – attack on Mexico City. By mid-September in 1847 the Americans had taken Mexico City. The Mexican government surrendered.

10. The Peace Treaty The Treaty of Guadalupe Hidalgo was signed in February 1848. Mexico gave up all claims to Texas and agreed to the Rio Grande as the border between Texas and Mexico. Mexico gave its provinces of California and New Mexico to the United States as part of the Mexican Cession. In 1853 the U.S. paid Mexico and additional $10 million for the Gadsden Purchase. With this purchase, the U.S. mainland reached its present size.