President James K. Polk, “Special Message to Congress on Mexican Relations” (May 11, 1846)
Instead of this, however, we have been exerting our best efforts to propitiate her good will. Upon the pretext that Texas, a nation as independent as herself, thought proper to unite its destinies with our own she has affected to believe that we have severed her rightful territory, and in official proclamations and manifestoes has repeatedly threatened to make war upon us for the purpose of reconquering Texas. In the meantime we have tried every effort at reconciliation. The cup of forbearance had been exhausted even before the recent information from the frontier of the Del Norte. But now, after reiterated menaces, 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.
On May 13, 1846, Congress declared war on Mexico.
PBS offers a collection of resources on the War With Mexico.
You can read more about Polk, his life and administration, the war with Mexico in Don’t Know Much About History, Don’t Know Much About the American Presidents and Don’t Know Much About the Civil War.
Don’t Know Much About® the American Presidents (Hyperion paperback-April 15, 2014)
