Polk Sends John Slidell To Mexico City

On November 10, 1845, Polk sent John Slidell, a secret representative, to Mexico City with an offer of $25 million ($628,942,308 today) for the Rio Grande border in Texas and Mexico’s provinces of Alta California and Santa Fe de Nuevo México.

U.S. expansionists wanted California to thwart British ambitions in the area and to gain a port on the Pacific Ocean. Polk authorized Slidell to forgive the $3 million ($75,473,077 today) owed to U.S. citizens for damages caused by the Mexican War of Independence and pay another $25 to $30 million ($628,942,308 to $754,730,769 today) in exchange for the two territories.

Prior to the Mexican-American War, Slidell was sent to Mexico, by President James Knox Polk, to negotiate an agreement whereby the Rio Grande River would be the southern border of Texas. He also was instructed to offer, among other alternatives, a maximum of $30 million for California by Polk and his administration. Slidell hinted to Polk hat the Mexican reluctance to negotiate might require a show of military force by the United States. Under the guidance of General Zachary Taylor, U.S. troops were stationed at the U.S./Mexico border, ready defend against Mexican attack. The Mexican government rejected Slidell's mission. After Mexican forces attacked at Matamoros the United States declared war on Mexico on May 13, 1846.