What Were the Causes and Consequences of the Mexican War?

The Mexican-American War was a "question of righteousness". On May 9th, 1846 President James K. Polk delivered a war message to Congress, stating that "Mexico has passed the boundary of the United States, has invaded our territory, and shed American blood upon the American soil." President Polk sent John Slidel to Mexico to negotiate a settlement. Slidell was authorized to purchase California and New Mexico, part of which was claimed by Texas, and to offer the U.S. government's assumption of liability for the claims of U.S. citizens in return for boundary adjustments. …