For John O'Sullivan, who coined the phrase, and other boosters of "manifest destiny," the concept was inextricably tied up with notions of Anglo-Saxon supremacy. O'Sullivan saw the United States, dominated by white Protestants, as a "great nation of futurity" (the title of one of his most famous essays) that was entitled, even obligated, to rule over lands formerly controlled by Mexico and Native Americans. In his 1845 essay "Annexation," O'Sullivan described the Mexican government as "imbecile and distracted," and asserted that it could no longer protect its territory of California:
The Anglo-Saxon foot is already on its borders. Already the advance guard of the irresistible army of Anglo-Saxon emigration has begun to pour down upon it, armed with the plough and the rifle, and marking its trail with schools and colleges, courts and representative halls, mills and meeting-houses. A population will soon be in actual occupation of California, over which it will be idle for Mexico to dream of dominion.
He went on to describe the Mexican people as a people of "mixed and confused blood," which he thought would allow them to incorporate African-American slaves from the South into their society, thus making the Southwest a "drain" through which African-American slaves might pass (a very common argument at the time). He wished an end to slavery, and thought the conquest of new territories would allow it to diffuse out of the Southeast.
To O'Sullivan, "Anglo-Saxon" and "American" were interchangeable terms, and both connoted democracy (only for white men) and progress. "We are," he told his readers in "The Great Nation of Futurity," published in 1839, "the nation of progress, of individual freedom, or universal enfranchisement." He envisioned a "manifest destiny" in which the white-dominated United States could not only exercise its dominion over territories controlled by supposedly racially inferior Mexican and Native American people, but rid itself of African-American people in the process. So "manifest destiny" was completely interwoven with nineteenth-century notions of white racial supremacy.