The Union defended Fort Sumter using cannons and a small contingent of infantry stationed at the fort.

The Union's defense of Fort Sumter relied mainly on cannons and infantry. Around 100 Union soldiers, commanded by Major Robert Anderson, were stationed at the fort, using their artillery to endure the Confederate assault. The fort's defenses featured multiple cannon positions designed to guard against attacks from the encircling Confederate troops. However, despite their efforts, the Union soldiers encountered insurmountable challenges during the fierce 34-hour bombardment that commenced on April 12, 1861. This defense ultimately led to the surrender of Fort Sumter, marking a crucial turning point at the beginning of the Civil War.