This Day in History

May 13, 1846:

President Polk Gets His War

 

This text comes from our 5th-7th grade textbook, From Sea to Shining Sea: The Story of America. For ordering information on this text and on our other books, please click here.

The United States and Mexico had not been friendly with each other. One reason for this unfriendliness was Texas. Ever since the revolution in 1836, Texas had been an independent republic. It had its own president, its own congress, and its own laws. Still, many Texians wanted to join the United States. Many people in the United States wanted this, too, but Mexico was against it. The Mexicans still said that Texas belonged to Mexico and so it would be unjust for the United States to take it. But the United States government ignored Mexico and in 1845 accepted Texas as part of the United States.

President Polk

James K. Polk, who became president of the United States in 1845, was one of those who thought the United States should spread from the Atlantic to the Pacific. He hoped Mexico would want to sell its lands west of the Rocky Mountains -- especially California -- to the United States. But the Mexican president was so angry about the United States having taken Texas that he refused to sell those lands. The United States and Mexico also disagreed over the southern boundary that divided Texas and Mexico. Mexico said it was the Nueces River, but the United States said it was the Rio Grande, a river lying 150 miles south of the Nueces River.

General Zachary Taylor, about 1845

If President Polk could not buy California from Mexico, he was willing to go to war to get it. In January 1846, he ordered General Zachary Taylor to lead his army across the Nueces River and march to the Rio Grande. Polk knew that Mexico would think this an act of war, for the Mexican government said this region was a part of Mexico. He hoped that the Mexican army would attack the American army. If this happened, Polk was sure the American people would become so angry that Congress would declare war on Mexico.

Everything happened just as Polk wished. General Taylor led his troops to the Rio Grande and laid siege to Matamoros, which lay on the south bank of the Rio Grande. For one month Taylor remained across the river from the city. Finally, on April 25, 1846, Mexican cavalry crossed the Rio Grande and skirmished with American soldiers, killing several of them.

Map showing Texas
and the region in dispute (in green)
between Texas  and Mexico

On May 11, President Polk appeared before Congress. Mexican soldiers had attacked American soldiers on American soil, he declared. This was, of course, not quite true, since there was no agreement that the land between the Nueces River and the Rio Grande belonged to the United States. It made just as much sense to say that the American army had invaded Mexico. If that was so, then, Mexico had the right to attack. But most people in the United States did not care about this; they were angry that American soldiers had been killed. So on May 13, Congress declared war on Mexico. James Polk had gotten the war he wanted....

Congressman Abraham Lincoln

Though most Americans were in favor of the war with Mexico, some opposed it. Antislavery people thought that adding more territories to the United States would mean that southern slavery would spread to new areas. These people had been against making Texas part of the country for the same reason. Some pro-slavery Southerners also opposed the war because they wanted no more fights with antislavery advocates over slavery in the new territories. Some Americans opposed the war because they thought it was unjust. President Polk, they said, had picked a fight with Mexico. One of these was the young congressman from Illinois, Abraham Lincoln. Lincoln said that since the Rio Grande had never been the southern boundary of Texas, it had been wrong for Polk to send General Zachary Taylor across the Nueces River. The United States, not Mexico, Lincoln said, had started the war.

  

Two Melodies from the War

These two pieces are instrumental versions of songs popular at the time of the Mexican-American War. The first, "Tejano Corrido," is a Mexican ballad (corrido); the second, is "Old Rosin the Bow, a version of an Irish folk song. (The second starts at 0:13.)

Alamo / Mexican American War Music / Tejano Corrido

 

Alamo / Mexican American War Music / Old Rosin the Bow