It could be said that the American Civil War was brought on by Americans need to expand its territories and the one sided Mexican War. The whole debate or controversy over this expansion was David Wilmot’s (and his squad of backers: Hamlin, Brinkerhoff, and King) trying to implement the Wilmot Proviso into the funding for the Mexican territories we acquired. The proviso actually fueled the debate over slavery into the newly acquired territories by trying to make the territories slave free acquisitions. The Wilmot Proviso was a simply desire to make newly acquired territories free from slavery.
As pointed out in the opening of this discussion however, banning slavery in these territories was a mute point in the fore front. So what impact did the Wilmot Proviso have on the debate over slavery in America? It actually seemed to create a debate were one did not actually exist. The debate or desire to ban slavery was created by Democratic House members (anti-slavery members) who were afraid that the Whig party would spin the War with Mexico into their desire to expand slavery.  So the very party that supported slavery issues had the desire to ban slavery in the new territories anyway.
Although these few anti-slavery Democrats did not represent the whole, the desire was there and they wanted the territories to be free. Given, this move was to keep the Whig party from making the accusations that the Democrats were moving to expand the real estate for slavery. McPherson, Battle Cry of Freedom: The Civil War Era, even points out that Congressman from the northern states tried to enact a proviso banning from the territories acquired by a war in which two-thirds of the volunteer soldiers had come from slave states. General Taylor was a slaveholder but opposed the expansion of slavery when he became president. 2] McPherson examines the irony of this fact as well as many other ironies that were to do with the Mexican War and the Civil War.
Another point that McPherson makes is that the men won the Mexican War because of the marksmanship and elan of their mixed divisions of regulars and volunteers and above all because of the professionalism and courage of their junior officers. Yet the competence of these men foreshadowed the ultimate irony of the Mexican War, for many of the best of them would fight against each other in the next war. 3] This is pretty powerful stuff that McPherson is feeding us, pointing out the fact that nearly the same group of men who fought the Mexican War would face one another again during the Civil War. The fact that they were so successful in the first led them to face one another in the second partly due to the Wilmot Proviso and other factors that revolved supposedly around the slavery issue. Taking a different avenue of approach on the supposed fact that slavery and the Wilmot Proviso was the cause and sole factor of the Civil War.
During and in the heat of the Wilmot Proviso debate, many southern lawmakers began to question the right of Congress to determine the status of slavery in any territory. According to John Calhoun, the territories belonged to all the states. Why should a citizen of one stated be denied the right to make his property, including slave, into territory owned by all? This line of reasoning began to dominate the southern argument.  So here now enters the government encroaching on the rights of the southern states and overreaching its authority to tell them what they could and could not do in their territories.
So, although slavery was the catalyst, the southerners began to turn the whole issue into “rights” issue that revolved around properties. The federal government began meddling in the rights of the states to govern its domain. So the fact that the Wilmot Proviso was trying to govern who and who “could not” have slaves was a violation of the state’s rights. The issue moved from one of abstraction to one involving practical matters. The nature of the Constitution, slavery, the value of free labor, political power, and ultimately political realignment were all involved in the debate. 5] The southerners started to become enraged at the fact they were being told what to do and how to do it. So what was the impact of the Wilmot Proviso on the debate over slavery in America? Some would say that the Wilmot Proviso is one of the top five reasons or causes for the Civil War and I might have to agree with that as well. In my opinion, the proviso just fueled the fire on the slavery debate simply due to the fact that it was pointless in the sense they were trying to impose a ban on in area that would have not really benefited from the use of slaves anyway.
The areas of Texas, Arizona, and California were not geographic areas where slaves would have made a great deal of difference anyway so the proviso was pointless to them. The proviso was trying to impose a ban on slavery in areas where there was to be little need for slaves anyway. So the proviso was just a platform to them to impose slavery bans in the south and expand their agenda on the issue. The southern states saw the proviso as an insult to the Southern states and their stand on slavery.
Of course, I do think they were moving in the right direction from a humanitarian standpoint they were going about it the wrong way. The debate should have been over the constitutionality of the issue all together and the rights of all men/women. They even entertained the thought of popular sovereignty but that would just have let the issue as is because the southern states would have left it like it was and the northern states would have moved to abolish it all together. Let us not forget that the southern states were not the only areas that possessed slaves.
The northern states and citizens did indeed possess slaves in large numbers and many of the politicians pushing the issue of banning it were slave owners themselves. So, in a hypocritical fashion, they were preaching one thing and practicing another. This could not have been favorable to their standpoint at all. Sounds a lot like our politicians today and the way they practice government of late. The point made and known today is that slavery was wrong, inhuman, and unjust and we know that today. The reasons or thought process they used then to justify what they were doing boggles the mind and makes you wonder.
It should have been made law without question and the Wilmot Proviso was a move towards that fact. The only ones that were offended or involved were the ones that were practicing this and most of those were wealthy farmers and beau crates and the most common of people could have cared less.
 http://blueandgraytrial. com/event/Wilmot_Proviso  James McPherson, Battle Cry of Freedom: The Civil War Era. Oxford Press 1988, p. 4  Ibid, p. 4  www. ushistory. org/us/30b  Michael F. Holt, The Political Crises of the 1850 s. 1978, p. 50