The correct answer is: Fort Sumter was located in a Union state and controlling it would make it easier to hold off Union troops.
Fort Sumter, located in Charleston Harbor, South Carolina, was a key strategic fortification for the Union. At the onset of the Civil War, the Confederacy sought to control Fort Sumter to strengthen their defenses against Union forces and to assert their independence. The fort's location in a Union state (South Carolina had seceded but the fort was still held by Union troops) made it a significant target for the Confederacy as it symbolized federal authority in the South. Taking control of the fort would also help prevent it from being used as a base for Union operations in the region.