Episode 3 of 3

Declaration of War

When: May 13, 1846
Where: U.S. Capital
Part of: Outbreak of the Mexican–American War over the disputed Texas border

The United States formally declared war on Mexico following the initial hostilities.

Following the Thornton Affair and the Battle of Palo Alto, the United States declared war on Mexico on May 13, 1846. President Polk used the attack on the U.S. patrol to convince Congress to declare war. This formal declaration followed the outbreak of open conflict in April.

Sources

Mexican–American War Wikipedia, revision of 2026-09-10

Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.