Texas Gains Independence
“Remember the Alamo” became a rallying cry for the Texans who were steadfast in their quest for independence. Weeks later, while Santa Anna's troops took their afternoon siesta, Texans attacked. They were under the command of Sam Houston, who had fought against the Native Americans with Andrew Jackson in the War of 1812. By the end of the Battle of San Jacinto, the Texans captured Santa Anna, who promised, in exchange for his life, that he'd retreat from Texas. Thus, the Republic of Texas (nicknamed “the Lone Star Republic” because its flag bore a single star) received its independence.
In the Mexican-American War's aftermath, Mexican Americans lived as second-class citizens in territory they once owned. Many lost their land and livelihoods. In addition, the war reopened the sticky issue of slavery.
Sam Houston immediately asked for Texas to be annexed to the United States, but as the balance of states stood at the time, there were thirteen states opposed to slavery and thirteen states in favor of it. Northerners felt that admitting Texas, where slavery was legal, would tip the balance of power in favor of the South. Thus, annexation was tabled until President John Tyler succeeded in pushing a joint resolution through Congress allowing Texas to join the Union in 1845.
The Mexican-American War
When annexation occurred, Mexico severed all diplomatic ties to the United States. Mexicans were even more outraged when U.S. officials insisted that the Rio Grande be used as the southern border of Texas. Thus, border skirmishes ensued even as the new president, James Polk, offered to purchase California and New Mexico and to assume Mexico's debts in exchange for the Rio Grande border. When rumors of Mexican invasion caught the capital's attention, the president sent General Zachary Taylor and 3,500 troops to the Rio Grande to defend Texas. After Mexicans killed several of Taylor's men, Polk asked Congress to declare war, which it promptly did.
The U.S. soldiers who marched across the dry ground became covered with a white dust, similar in color and texture to Mexican adobes. Soon, Mexicans dubbed their opponents “dobies” or doughboys, and the name stuck for generations of soldiers.
It didn't take long to capture California, and Americans also forced a Mexican surrender at Monterrey. Yet the war effort met with criticism, for some saw this as an aggressive, unprovoked war on disputed territory. Undeterred, President Polk ordered troops south to capture Mexico City. Shortly thereafter, both sides reached peace.
Protesters against the Mexican War claimed it was immoral, proslavery, and against Republican values. Henry David Thoreau refused to pay his state (Massachusetts) taxes in protest and was placed in jail. Inspired by his arrest, Thoreau wrote Civil Disobedience, which was studied by many, including Mahatma Gandhi and Martin Luther King.
After two years of fighting, the Treaty of Guadalupe Hidalgo resulted in Mexico's ceding California and large stretches of the Southwest to the United States, as well as its acceptance of the Rio Grande border. In return, the United States paid the Mexican government $15 million and assumed unpaid claims by U.S. citizens against Mexico. Zachary Taylor emerged as a hero and was elected president in 1848.

