What role did the problem of slavery play in the confrontation between the North and the South?

The North insisted on freeing the slaves. At the same time, the South was against it. It was the southern states that were considered slave-owning. In addition, there were other disagreements between the parties, which led to the outbreak of the war. Over time, the northern states were able to take advantage of the liberation of blacks from slavery. So for the entire period of the war the ranks of the northern army were replenished with 200 thousand blacks, which became a weighty counterbalance to the war with the South. Ultimately, the US wins, for this reason slavery has been abolished throughout America.