Mexican American War and Manifest Destiny

Mexican-American War

​In an 1845 magazine article supporting the annexation of Texas, John O'Sullivan suggested that it was the nation's manifest destiny, or obvious fate, to settle land all the way to the Pacific Ocean. This idea that American expansion was inevitable proved very popular.

​In the 1840s and 1850s, manifest destiny was tied up with the slavery issue. If America expanded, would slavery be allowed in the new territories? Several presidents became involved in the difficult issue, including President John Tyler. A pro-slavery Whig, Tyler wanted to increase the power of the southern slave states by annexing Texas. His fellow Whigs disagreed.

​Mexican Borderlands

​Though it had lost Texas, Mexico still had settlements in other areas of the present-day Southwest to govern. New Mexico was the oldest settled area, with its capital at Santa Fe. Mexico also had settlements in present-day Arizona, Nevada, and California.

​After winning independence from Spain in 1821, Mexico began to change old Spanish policies toward California and Texas. In 1833, for example, Mexico ended the mission system in California. Mission lands were broken up, and huge grants were given to some of the wealthiest California settlers, including Vallejo. They created vast ranchos, or ranches, with tens of thousands of acres of land. Vaqueros, or cowboys, managed the large herds of cattle and sheep. Cowhides were so valuable that they were called “California banknotes.” Hides were traded for household items and luxury goods from the eastern United States.

​Conflict Breaks Out

​Mexico had long insisted that its northern border in Texas lay along the Nueces River and refused to accept Texas annexation as legitimate. The United States said the border was farther south, along the Rio Grande. In June 1845 President Polk ordered General Zachary Taylor to lead an army into the disputed region.

Multiple Choice

Who was the president of the United Stated during the Mexican-American War?

• James K. Polk

• Thomas Jefferson

• James Monroe

• George Washington

Multiple Choice

What river did Mexico believe was the border between Texas and Mexico?

• Nueces River

• Mississippi

• Colorado

• Red River

​Polk sent diplomat John Slidell to Mexico City to try to settle the border dispute. Slidell came with an offer to buy New Mexico and California for $30 million. Mexican officials refused to speak to him. In March 1846 General Taylor led his troops to the Rio Grande. He camped across from Mexican forces stationed near the town of Matamoros, Mexico. In April, the Mexican commander told Taylor to withdraw from Mexican territory. Taylor refused. The two sides clashed, and several U.S. soldiers were killed.

​President Polk

Multiple Choice

Who was the commander of U.S. forces in Texas and led the United States forces against Mexico?

• John Slidell

• Stephen Kearney

• John C. Freemont

• Zachary Taylor

​War Begins

​At the beginning of the war with Mexico, the U.S. Army had better weapons and equipment. Yet it was greatly outnumbered and poorly prepared. The government put out a call for 50,000 volunteers. About 200,000 responded. Many were young men who thought the war would be a grand adventure in a foreign land.

​In 1846 only about 500 Americans lived in the huge province of California, in contrast to about 12,000 Californios. Yet, in the spirit of manifest destiny, a small group of American settlers seized the town of Sonoma, north of San Francisco, on June 14. Hostilities began between the two sides when the Americans took some horses that were intended for the Mexican militia. In what became known as the Bear Flag Revolt, the Americans declared California to be an independent nation.

​The two armies clashed at Buena Vista in February 1847. Taylor used his artillery to his advantage. After a close battle with heavy casualties on both sides, the Mexican army retreated. The next morning, the cry went up: “The enemy has fled! The field is ours!”

Multiple Choice

Why did President Polk want Mexican territory?

• He wanted to expand the US
• The land had good resources
• He needed room to build a mansion for his cats
• To get Shrek'd

Multiple Choice

Why did the U.S. and Mexico go to war?

• All of these answers are correct
• The U.S. and Mexico disagreed over their boundary
• America's continued desire to achieve manifest destiny
• The U.S. recently annexed Texas

Multiple Choice

Which of the following is an opinion about Manifest Destiny?

• It reached the height of its popularity during the 1840s
• Its goals were racist and unethical
• Its goals required the U.S. to acquire Mexican land
• Its supporters were pleased by the outcome of the Mexican-American war

​A beloved leader, Scott was known by his troops as “Old Fuss and Feathers” because of his strict military discipline. Scott sailed to the port of Veracruz, a major port and the site of the strongest fortress in Mexico. On March 29, after an 88-hour artillery attack, Veracruz fell. Scott moved on to the final goal, Mexico City, the capital.

​After a truce failed, Scott ordered a massive attack on Mexico City. Mexican soldiers and civilians fought fierce battles in and around the capital. At a military school atop the steep, fortified hill of Chapultepec, young Mexican cadets bravely defended their hopeless position. At least one soldier jumped to his death rather than surrender to the invading forces. Finally, on September 14, 1847, Mexico City fell. Santa Anna soon fled the country. Scott’s capture of the Mexican capital led to the end of the war.

​The war ended after Scott took Mexico City. In February 1848 the United States and Mexico signed the Treaty of Guadalupe Hidalgo, which officially ended the war and forced Mexico to turn over much of its northern territory to the United States. Known as the Mexican Cession, this land included the present-day states of California, Nevada, and Utah.

Multiple Choice

Mexico won the war.

• True
• False

Multiple Choice

Which treaty ended the war?

• The treaty of Guadalupe Hidalgo

• The treaty of Paris

• The treaty of Canada

• The treaty of the United States