The Mexican-American War
The Mexican-American War (1846-1848) - Also
referred to as the Mexican War or the U.S.-Mexican War, this armed
conflict occurred after the 1845 U.S. annexation of
Despite the 1836
Texas Revolution, Mexico still
considered her part of its territory. The Mexican Congress never
recognized Texan independence, seeing the Republic as a rebellious
territory that would eventually be retaken. After the annexation of
as a state in December, 1845, Mexico immediately broke off
diplomatic relations with the United States and disputes arose as to
the southern boundary of
Texas, which had now become the southern
boundary of the United States. The Mexicans said that
only to the Nueces River, while the Texans declared that it extended
to the Rio Grande River.
Territorial expansion of the United States to the
Pacific Coast was the goal of President James K. Polk, who proceeded
to defend the territory of its new state. Though the war was highly
controversial, with the Whig Party and anti-slavery elements strongly
opposed, Polk ordered
General Zachary Taylor to lead his forces to the
Rio Grande River.
William Huddle’s 1886 depiction of the end of
shows Mexican General Santa Anna
surrendering to the wounded
Sam Houston after the
Battle of San Jacinto in 1836.
In January, 1846, Taylor and 4,000 soldiers, marched to
the Rio Grande River but, were ordered not to attack the Mexicans.
However, Taylor’s orders also required that he defend himself and his
troops if the Mexicans instigated an assault. The troops initially
spent their time patrolling the new border and scouting to see if any
Mexican soldiers had crossed the Rio Grande River.
On April 25th, a company of some 70 Dragoons, commanded
by Captain Seth Thornton, was scouting parts of the disputed area
about 20 miles northwest of what is now Brownsville,
mission was to determine whether or not the Mexican Army had crossed
the Rio Grande for a possible attack on
Fort Texas (later called
Fort Brown.) Acting on the advice of a local guide, the troops went to
investigate an abandoned hacienda. What they found were 2,000 Mexican
soldiers under the command of Colonel Anastasio Torrejón encamped in
and around the hacienda.
Fighting immediately broke out and though the
vastly outnumbered U.S. troops fought ferociously, they were forced to
surrender after several hours of resisting. Known as the Thornton
Affair, Thornton Skirmish or Thornton's Defeat, 16 U.S. Dragoons were
killed and five wounded, including Captain Thornton. One U.S.
cavalryman; however, was able to escape and made it back to camp,
reporting of the Mexican opening of hostilities. Fifty men, including
Captain Thornton, were taken prisoner and held at Matamoros,
Upon learning of the incident, President Polk asked for
a declaration of war before a joint session of the United States
Congress and on May 13, 1846, Congress declared war on Mexico.
The first battles were fought in
Texas, which included
the Siege of Fort Texas, the Battle of Palo Alto, and the Battle of
Resaca de la Palma. After these decisive victories, General Taylor
began a campaign invading Mexican territory.
In Mexico, Taylor and Mexican leader, General Santa
Anna, fought a desperate battle at Buena Vista in February, 1847.
Though the U.S. troops were greatly outnumbered, General Taylor placed
his men so skillfully, that he won a victory that put an end to the
campaign in northern Mexico. However, this defeat as well as other
skirmishes did not serve to induce the Mexicans to give up all the
territory that the United States demanded, so it was determined to
send an army directly to the enemy's capital in Mexico City.
President Polk sent a second army under General Winfield
Scott, which was transported to the port of Vera Cruz by sea, to begin an
invasion of the Mexican heartland. On March 9, 1847, Scott landed at the
chief Mexican seaport on the eastern coast and captured the city.
From there, Scott and his army marched to Cerro Gordo,
where the road to the capital city passes through the mountains. His plans
were so skillfully made and carried out that the Mexican army was defeated
at that place and again at Pueblo. The Americans were now in the heart of
Mexico, far away from their base of supplies and opposed by an army of
many times their own numbers, but they pressed on and captured the
defenses of the city.
In the meantime, citizens in
California, which was still a
part of the Mexican Republic, also began to rebel. Unhappy with the way
that the Mexicans treated them, they established a republic of their own
and asked the U.S. Government for help. Under the command of Commodore
Robert F. Stockton, several naval vessels were sent to the Pacific Coast.
Captain John c. Fremont of the U.S. Army also arrived to aid the
New Mexico, General Stephen W. Kearny with a
strong expedition was sent to capture the old Spanish-Mexican town of
Santa Fe, which he did with little trouble, before marching on to
California. With the help of U.S. troops, the last battle was fought in
California on January 9, 1847 and on January 12th, the last
significant body of Californians surrendered to U.S. forces, marking the
end of resistance in California.
After a series of United States victories, the Treaty of
Guadalupe Hidalgo, signed on February 2, 1848, ended the two year war. In return for $18,250,000,
Mexico gave the U.S. undisputed control of
Texas, with its border at the
Rio Grande River, and the U.S. agreed to withdraw her armies from Mexico.
The treaty also required Mexico to abandoned her claims to
New Mexico, and other lands which are now included in the
When the boundary line came to be surveyed, the American
and Mexican commissioners could not agree. In the end, in 1853, the United
States paid Mexico ten million dollars more and got in return a strip in
the extreme southern parts of
New Mexico, thus making the
southern boundary of the United States as it is today.
of America, updated September, 2016.
Bragg, Lee, Grant, and Davis
in the Mexican War
For the first time in the
Mexican War, graduates of the U.S. Military Academy held a majority
of field and staff officer positions. General Scott later commented
that without these officers the war would have lasted longer and
been much more costly. The West Pointers vindicated themselves and
the academy in the eyes of many average Americans. The Mexican War
also proved to be a training ground for men like
Ulysses S. Grant, and