What was the civil war about?

The civil war started when the slave & the non-slave states sought for power in the national government.

Populations;
Slave; 9 million
non-Slave; 22 million

When the war broke out, the North and the south had fought for over 4 years until the South had surrendered and the North was victorious. The states then returned back to the union.

The amount of people that died compared to other wars the nation had fought are shown in the graph by google.