The main cause of southern succession was the US 's inability to solve the issue of slavery at national level.
Step-by-step explanation:
The primary cause of the civil war was that the southern states desired to preserve the institution of slavery. Northerners opposed to the expansion of slavery .
Some opposed it due to moral reasons and others felt that slave labor was unfair. When Abraham Lincoln was elected as president in 1960 seven southern states seceded from the Union.
The secessionists claimed that according to constitution every state has right to leave the union.