Answer:
The Union strongly believed that black people were meant to have free will and fought to abolish slavery. The Union far outclassed the Confederates in manpower, resources (with the exclusion of cotton) and weapons. The Union was in control of more land and had a bigger army than the Confederates.
Explanation:
Because the social, political and economical situation after WW1 allowed them to raise. It was just a small party until 1930. But after the big depression they utilised the fear of the people and gained influence.