On May 11, 1846, US President James K. Polk spoke before Congress, urging the country’s legislators to declare war on neighboring Mexico:
…Mexico has passed the boundary of the United States, has invaded our territory and shed American blood upon the American soil. She has proclaimed that hostilities have commenced, and that the two nations are now at war.
As war exists, and, notwithstanding all our efforts to avoid it, exists by the act of Mexico herself, we are called upon by every consideration of duty and patriotism to vindicate with decision the honor, the rights, and the interests of our country…
In further vindication of our rights and defense of our territory, I invoke the prompt action of Congress to recognize the existence of the war, and to place at the disposition of the Executive the means of prosecuting the war with vigor, and thus hastening the restoration of peace… .
The United States would officially declare war on Mexico two days later. The Mexican-American war, which would go on to cost Mexico much of its northern territory, had begun.
