Why did the Fort Sumter battle happen?

By April of 1961, when Ft. Sumter was attacked, the

Southern states

had seceded from the Union. They considered themselves to be an independent nation no longer under the control of the

United States

.

However, the United States (the North) did not recognize that the South (the Confederacy) was independent. And there were a number of United States military facilities in the South that still had

Northern troops

in them. Ft. Sumter was one of them. Since the South didn't consider itself a part of the United States anymore, they were not about to allow U.S.

troops to be on their soil. So they attacked to get rid of them.

And that's how the Civil War started.