The long-running debate about the enslavement of African American people was the main cause of the start of the American Civil War. Just over a month after Abraham Lincoln took office as President of the United States, Confederate forces assaulted Fort Sumter in South Carolina in April 1861, sparking the start of the American Civil War. The Union loyalists in the North, which included some geographically western and southern states, declared their support for the Constitution. They were opposed by Confederate States of America secessionists in the South, who campaigned for states' rights to keep slavery.
One of the most important turning points in American history, the American Civil War continues to be the deadliest conflict ever fought on American soil. From 1861 to 1865, more than 620,000 people perished, which was more than the number of American soldiers who died in all other wars put together. The war had a significant impact on the identity of the United States, since it led to the freedom of African Americans during the Reconstruction Era and contributed to the formation of a more unified national identity.