O'Sullivan's essay urged that "It is now time for the opposition to the Annexation of Texas to cease." O'Sullivan argued that the United States had a divine mandate to expand throughout North America, writing of "our manifest destiny to overspread the continent allotted by Providence for the free development of our
The United States was justified in going to war because Mexico had shed American blood on American soil, Texas was an independent republic and had the right to govern itself, and Texas was trying to become part of the United States
