How did the American Civil War Actually Happen? (Part 1)

How did the American Civil War Actually Happen? (Part 1)
The American Civil War (1861-1865) was fought over deep tensions between the Northern and Southern states of the United States, particularly over slavery, states' rights, and western expansion. The sharp economic divide between the industrial-focused North and the slave-based agricultural South exacerbated the situation.
Tensions escalated with the election of Abraham Lincoln as president in 1860, prompting seven Southern states to secede and form the Confederacy. After the attack on Fort Sumter by Confederate forces in April 1861, the full war between the North (Union) and the South (Confederate) began.