Fort Sumter was built as a first line of defense for the United States before the war. During the Southern secession, there were soldiers that were loyal to the union in the south. 5 days after South Carolina seceded from the Union, on Christmas, 68 Union troops moved away from the cities into Fort Sumter as to not cause any troubles. Confederate states did not like that there were Union soldiers in southern forts. Many times they had demanded that the Union should leave the the Confederate States.
The fort was built with 5 sides and made out of bricks. It is located on a manmade island on the Charleston Harbor. The construction of the fort began in 1829 and was in progress into the beginning of the civil war. It was named after the Revolutionary War general, Thomas Sumter. The forts 60 guns faced out to sea, leaving no reason for the Union to need the fort, except one, to keep union between the States.