The annexation of Texas
The Whigs in Congress opposed the concept of manifest destiny, deriding its reference to Divine Providence as a means of justifying actions which were motivated by more secular goals. While the argument over the Oregon dispute went on the new phrase was seized by the Democrats as justification for the annexation of Texas, which had been requested by the Republic of Texas, although the area was still claimed by the Mexican government as its territory. Annexation of Texas was a major issue of the 1844 Presidential election, along the same lines as the Oregon dispute. That year President Tyler negotiated a treaty of annexation with Sam Houston and presented it to the Senate.
The Senate overwhelmingly defeated the annexation treaty in June, 1844. After Polk won election that fall Tyler presented the treaty to both houses, which passed them after entering a compromise which provided the incoming Polk the option of annexation or renegotiation of the treaty. Tyler presented the bill to the Texas government on his last day of office and the incoming Polk urged Texas to ratify, which it did, and Texas formally entered the United States as the 28th state, officially yielding sovereignty in February 1846. Because of yet unresolved issues with Mexico, relations deteriorated rapidly, and the Mexican-American War began later that year.
The land between the Nueces and Rio Grande Rivers was disputed throughout the existence of the Republic of Texas, and remained unresolved after annexation. After Polk offered to compensate the Mexican government if it accepted the Rio Grande as the southern border, which they rejected, he placed American troops in the disputed area. After a clash of forces in the disputed area Polk announced that American territory had been invaded and Congress declared war. There was little debate. During the lead up to the war the cries of manifest destiny, in reference first to the annexation of Texas and then the seizure of the disputed territory were loud among the southern Democrats.
The Americans held several advantages in the Mexican War, the first in which graduates of the United States Military Academy took part, and several early victories increased the cries of manifest destiny to include the US seizure of all of Mexico. Senator John C. Calhoun was a supporter of manifest destiny and the annexation of Texas (a slave state) but opposed the annexation of Mexico. “We have never dreamed of incorporating into our Union any but the Caucasian race…” he argued in the Senate. Calhoun thus distanced himself from the duty aspects of manifest destiny for racial causes. The annexation of Mexico would have meant the granting of American citizenship to Mexicans, non-whites for the most part.
The debate continued as the war went on, with many in the east arguing for the annexation of all Mexico, which at the time included all of California and what later became the states of Colorado, New Mexico, Arizona, Nevada, Utah, and parts of others. The manifest destiny argument was promoted by much of the North, and abandoned by much of the South. The Northern contingent believed it would promote national security and forever secure an anti-slavery majority, the South opposed it for racial and religious reasons, fearful of an introduction of a large number of Catholics. The issue was still being debated when peace commissioners met following Mexico’s military defeat.