I did some reading. The fort was being starved out. Lincoln offered to resupply with provisions, but not war .materiel. But some sources say that one of the resupplying ships was a gunship. They were ALL gunships except the "Uncle Ben" and the "Baltic" (which was a troop ship carrying troops) All of the rest of them mounted cannons.
Also there were at least 200 reinforcement troops on the "Baltic", as well as powder, shot, rifles, mortars, fuses and pretty much everything Lincoln said would not be put into the fort if the supply mission was allowed to continue.
Major Anderson was going to evacuate the Fort peaceably if Lincoln had just allowed him one more day. He had already written the evacuation order.
Here are some newspaper clippings from the New York Times from early April of 1861.
The fort was being starved out. Lincoln offered to resupply with provisions, but not war .materiel. But some sources say that one of the resupplying ships was a gunship. Several of the ships were armed. And they were carrying men and munitions to be landed at Sumter if the resupply was opposed. But had the South not chosen to start the war, the fleet would have done nothing but land food and supplies, no reinforcements or munitions.