American War With Mexico 1846–1848
Belligerents
The United States of America.
Mexico.
Cause
Texas seceded from Mexico in 1836. The independence of Texas was recognized by the United States, but the proposal that the new state should be admitted into the Union was declined. A strong support for the annexation of Texas in the interests of slavery grew up, more especially in the Southern states, and in December 1844 resolutions were passed in both Houses, and it was formally enrolled as a new state.