<P> When Texas was annexed , Mexico broke diplomatic relations with the United States . The annexation bill did not specifically define the boundaries of Texas . The former republic claimed the Rio Grande as its southern border , while Mexican authorities had always considered the Nueces River , situated further north , to be the boundary of Mexican Texas . The United States sent John Slidell to negotiate with the Mexican government , offering l $25 million ( $692,019,231 today ) to set the Texas border at the Rio Grande and to purchase Mexico 's provinces of Alta California and Santa Fe de Nuevo México . Popular sentiment in Mexico was against any sale , and the army deposed President José Joaquín de Herrera when he appeared inclined to negotiate with Slidell . </P>
<P> When Texas was annexed , Mexico broke diplomatic relations with the United States . The annexation bill did not specifically define the boundaries of Texas . The former republic claimed the Rio Grande as its southern border , while Mexican authorities had always considered the Nueces River , situated further north , to be the boundary of Mexican Texas . The United States sent John Slidell to negotiate with the Mexican government , offering l $25 million ( $692,019,231 today ) to set the Texas border at the Rio Grande and to purchase Mexico 's provinces of Alta California and Santa Fe de Nuevo México . Popular sentiment in Mexico was against any sale , and the army deposed President José Joaquín de Herrera when he appeared inclined to negotiate with Slidell . </P>
who was sent to the rio grande to claim the southern border of texas
who was sent to the rio grande to claim the southern border of texas
John Slidell
John Slidell