The War with Mexico

1846-1848

When the US admitted Texas to the Union, Mexico cut off all diplomatic ties w/ the US

To make is worse, the US insisted that the Rio Grande was the southern border of Texas

Mexicans were outraged. They claimed the Texas border ended 150 miles to the north, at the Nueces River.

Even when Texas was part of Mexico, Texans never settled below the Nueces River.

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Early Issues Leading to WarTensions between Mexico and the United States, which had always been present, flared up with the U.S. annexation of Texas in 1845.The issues between the two countries could have been solved peaceably if not for the weak Mexican government and the stubbornness of American president James Polk.

He had “lost” parts of Oregon and needs to do well.

Early Issues Leading to War Polk sent John Slidell to Mexico in 1845 to try to convince the Mexicans to sell California and New Mexico to the U.S. in exchange for the Rio Grande borderThe Mexican leader, Jose Herrera, refused to talk to Slidell.

John Slidell

Early Issues Leading to War Polk realized the only way to gain these territories was to wage war against Mexico.He ordered General Zachary Taylor to blockade the Rio Grande to try to provoke the Mexicans.American troops stationed on another country’s land when no war declared…yet

Taylor’s Army

Early Issues Leading to War

Polk himself told Slidell to back off and return.

But Slidell went ahead and signed the agreement anyway.

John Slidell

Attitudes of Americans Towards a War with Mexico

Southerners were initially opposed to a war with Mexico, but later changed their minds when they realized that Texas could be brought in as a slave state.

Northerners generally saw the war as a southern plot to spread slavery. Many felt it wrong that Mexican blood would be sacrificed for the debate over the issue of slavery.

The War begins…

The U.S. violates Mexican territory by invading California.

Mexico sends troops across the Rio Grande and in a minor skirmish, 11 Americans are killed.

Polk calls for warPresident James Polk goes to Congress and asks for a declaration of war.Lincoln called for the “Spot Resolution” where the exact spot of aggression against US could be noted.The resolution failed.War is declared and the U.S. Army invades Mexican territory.

New Mexico falls without a shotCol. Stephen Kearney marched his troops 800 miles across Kansas and invaded New Mexico. The New Mexican Army joined with Kearney, and the territory of New Mexico fell to the Americans without any casualties.

The U.S. gains the territory of California

Californian settlers led by John Fremont declared their independence from Mexico and created the “Bear Flag Republic.”Col. Kearney marched on to California and joined forces with Fremont and defeated the Mexican Army. As a result, the U.S. gained control of California.

The War in MexicoThe U.S. invades Mexico in a war that lasts about a year.

The port of Monterrey is captured by General Taylor.

The war in Mexico winds down

After a series of battles, the Mexican Army, led by General Santa Anna, surrenders and Mexico City falls to General Winfield Scott.

A peace treaty brings new lands to the U.S.

At the conclusion of the Mexican War, the Treaty of Guadalupe Hidalgo is signed.As a result of the treaty, the U.S. gains the territories of California, New Mexico, Nevada, Utah, and most of Arizona, Colorado, and Wyoming.Next to the Louisiana Purchase, it was the largest gain of territory in U.S. history

Land gained by the Treaty of Guadalupe Hidalgo

The Gadsden Purchase completes America’s Manifest Destiny.

In 1853, President Franklin Pierce pays Mexico $10 million to purchase land along the U.S.-Mexican border.

The additional territory was called the Gadsden Purchase.

It completed the current border of the 48 states.

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Ralph Waldo Emerson

“the United States will conquer Mexico,

but it will be as the man swallows the

Arsenic, which brings him down in

turn. Mexico will poison us.”

Slavery will be the poison.

Jefferson’s Empire for Liberty had mostly become an Empire for Slavery.Territorial acquisitions since the Revolution had added slave states (LA, MO, AK, FL, TX) and only one non-slave state - Iowa.Many northerners feared similar future for new southwestern empire. They condemned the war as “slave power conspiracy”Was not President Polk a slave holder? Had he not been elected on platform of enlarging slave territory by annexing Texas? Were not the pro-slavery southerners the strongest proponents of Manifest Destiny?Polk didn’t get what the fuss was about. Unlikely that Mexican land would support any agriculture that used slavery

“The right to carry slaves to NM or California is no very great matter,” said John J. Crittenden of KY, because, “no sensible man would carry his slaves there if he could.”

Just to make sure, the northern congressmen voted for the Wilmot Proviso to exclude slavery from lands gained from Mexico.

It was not about slavery - it was about power within the Congress and within the party

Wilmot ProvisoNormal division in Congress had always been over party lines on issues such as the tariff, the Bank, federal aid to internal improvements, etcThe Wilmot Proviso changed all of that! Now politics was all about sections!The political landscape would never be the same again!