South Carolina seceded on December 20, 1860, the first state to do so. On January 9, Star of The West, a supply ship, attempted to reach the fort, but warning shots were fired, and the ship fled.
On February 15, the Confederate Congress declared that all Union forts must be "either by negotiation or force". Major Robert Anderson, commander of Fort Sumter, refused their demand of surrender.
By April 6, Sumter was the last federal installation that hadn't been coerced into surrender or been seized. Lincoln sent word to the South that a ship would be sent, with nothing but food in it. There would be no reinforcements, no ammunition, just humanitarian aid.
The South's answer was sent April 12 at 4:30am, as the Confederate guns unleashed. They would fire on the fort for thirty-three straight hours. Over four thousand shells were fired by the time the fort surrendered.
The war between the states had begun, and would last until April 8, 1865.