In 1846, Pennsylvania’s David Wilmot put forth his proposed proviso stating that “neither slavery nor involuntary servitude shall ever exist in any part of said territory, except for crime, whereof the party shall first be duly convicted.” This proposed proviso would then apply therefore to the territory so acquired from Mexico, as the end result of the Mexican-American war, in which, the United States was able to get Mexico to cede what became the States of California, Nevada, Utah, and New Mexico, as well as the majority of Arizona and Colorado, and also parts of Oklahoma, Kansas, and Wyoming. In addition, Mexico relinquished what became the State of Texas to the United States. In short, the point of the Wilmot Proviso was to make it national policy that the new territory won through what many considered to be an unjust war, would not then be utilized on behalf of the expansion of slavery. In other words, the point of the Wilmot Proviso was to keep slavery confined within the States where it currently existed, and thereby not to spread this inimical abomination of humans enslaving other humans any further than it already existed within these United States.
The Wilmot Proviso though was not passed and therefore was not ratified, and did not thus become the law of the land. The result of this legislation not being approved was the inevitable increase of slavery into what became new States, that previously did not have slavery because Mexico had abolished slavery from their nation in 1837. In other words, some of this previous Mexican territory, such as Texas became a slave State and also slavery was made legal in the New Mexico, Utah, and Indian territories. That is to say, those of the South made it their point to take territories so bought or won in war by the United States, so as to expand such into those additional States so created, as much as they could, such as in Louisiana and Missouri, which became slave States.
It is quite unfortunate, that the Wilmot Proviso did not become the law of the land, and to demonstrate how forward-thinking this proviso was, we need only look at the words of our 13th Amendment to the Constitution, which states, “Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States…” These words of the 13th Amendment are essentially the same as that proviso, with the basic caveat being that in order for the 13th Amendment to become the law of the land, there first had to be fought a bloody and extended civil war, which cost the lives of 620,000 Americans.
Indeed, in a land that celebrates freedom, justice, and liberty for all, there was never a point in which slavery could be justified within that national mindset -- yet, slavery was legal within the Constitution so ratified. Still, the principle of permitting slavery as understood by those legislators working within the construct of the Constitution was that they believed that by abolishing the slave trade as of 1808, that slavery would in time, cease to exist. Regrettably though, through territorial expansion, this renewed and reinvigorated those who saw the personal benefits of that slavery, and therefore they decided to do whatever that they had to do, to expand such into territories so bought or won through war, which led to the inevitable conflict of which a house divided, would not stand; but from the ashes of that great civil war, came the foundation that had previously been declared through its independence of those immortal words that “all men are created equal.”