The major cause had been on the grounds of slavery. This is because there had to be attempts made to abolish slavery or at least minimize it. There had been attempts made by the North to ensure that there would not be any black slaves at all. Therefore, there would only be whites working as laborers in the North. However, there had not been any intention shown by the controllers of the South to abolish slavery. This is because there had been attempts to continue to enjoy the facilities obtained from slavery in western territories.