How did the missouri compromise and the nullification crisis demonstrate increasing sectional competition and disagreements over slavery?

Many Southerners felt slavery was an economic necessity. Many Northerners felt that slavery was morally wrong. Northern factories wanted tariffs to help their industry which hurt Southerners buying goods in Europe with their cotton exports. When Calhoun wanted to nullify the tariff, Andrew Jackson said he would  bring in the US Army to stop him. The Missouri Compromise was done to keep the number of slave and free states equal. These were band aids to keep the country together and worked until 1861, when South Carolina seceded from the Union.