what were the theories behind manifest destiny how did it shape american policy
And that claim is by the right of our manifest destiny to overspread and to possess the whole of the continent which Providence has given us for the development of the great experiment of liberty and federated self-government entrusted to us.anifest Destiny played an important role in the expansion of Texas and American relationship with Mexico. In 1836, the Republic of Texas declared independence from Mexico and, after the Texas Revolution, sought to join the United States as a new state.