Here are the completed sentences:
Fort Sumter was a Union fort.
It was located in ** Confederate** territory.
Abraham Lincoln ordered food and supplies to be delivered to Fort Sumter in April 1861.
Confederate forces wanted to prevent these supplies from reaching the troops at Fort Sumter.
Confederate forces demanded that the commander of Fort Sumter surrender, but the commander refused.
Union forces surrendered and withdrew from Fort Sumter after the battle.