From Son of the South:
S. C. Major Anderson had long urged his government, but in vain, to strengthen the military works in Charleston Harbor. The burden of the few replies was: “Be prudent; be kind; do nothing to excite the South Carolinians. It will not do to send you reinforcements, for that might bring on hostilities.” At length he was satisfied that the people were about to attempt to seize Fort Sumter.
[..] he resolved to take position in Sumter before it should be too late. He was commander of all the defenses of the harbor, and, in the absence of orders to the contrary, he might occupy any one he chose.
Governor Pickens sent a message to Anderson demanding his immediate withdrawal from [the fort]. The demand was politely refused and, the Major was denounced in the State convention, in the legislature, in public and private assemblies, as a “traitor to the South,” […]. The Confederates in Charleston and Washington were filled with rage.
[Secretary of War] Floyd declared the “solemn pledges of the government” had been violated by Anderson and he demanded of the President [Buchanan] permission to withdraw the garrison from Charleston Harbor. The President refused; a disruption of the cabinet followed. Floyd fled; and Anderson received (Dec. 31) from Secretary of War [Joseph] Holt —a Kentuckian like himself— an assurance of his approval of what he had done.
Governor Pickens, nettled by Anderson’s refusal to give up Sumter, treated him as a public enemy within the domain of South Carolina. Armed South Carolinians had been sent to take possession of Fort Moultrie, where they found the works dismantled.
On February 7, […] seven states adopted a provisional constitution for the Confederate States of America and established their temporary capital at Montgomery, Alabama. A February peace conference met in Washington, D.C. but, failed to resolve the crisis. The remaining eight slave states declined pleas to join the Confederacy.
The seceding states seized numerous Federal properties within their boundaries, including buildings, arsenals and fortifications. President James Buchanan protested but, took no military action in response. Buchanan was concerned that an overt action could cause the remaining slave states to leave the Union and, while he acknowledged there was no constitutional authority for a state to secede, he could find no constitutional authority for him to act to prevent it.
South Carolina authorities considered Anderson’s move to be a breach of faith. Governor [Francis W.] Pickens believed that President Buchanan had made implicit promises to him to keep Sumter unoccupied and suffered political embarrassment as a result of his trust in those promises. Buchanan, a former U.S. Secretary of State and diplomat, had used carefully crafted ambiguous language to Pickens, promising that he would not “immediately” occupy it. From Major Anderson’s standpoint, he was merely moving his existing garrison troops from one of the locations under his command to another.
Governor Pickens […] ordered that all remaining Federal positions except Fort Sumter were to be seized.
President Buchanan was surprised and dismayed at Anderson’s move to Sumter, unaware of the authorization Anderson had received. Nevertheless, he refused Pickens’s demand to evacuate Charleston harbor. Since the garrison’s supplies were limited, Buchanan authorized a relief expedition of supplies, small arms, and 200 soldiers. […] an unarmed civilian merchant ship, Star of the West [was sent], which might be perceived as less provocative to the Confederates. As Star of the West approached the harbor entrance on January 9, 1861, it was fired upon by a battery on Morris Island, […] staffed by cadets from The Citadel […].
In a letter delivered January 31, 1861, Governor Pickens demanded of President Buchanan that he surrender Fort Sumter because, “I regard that possession is not consistent with the dignity or safety of the State of South Carolina.”
On March 4, 1861, Abraham Lincoln was inaugurated as president. He was almost immediately confronted with the surprise information that Major Anderson was reporting that only six weeks of rations remained at Fort Sumter. A crisis similar to the one at Fort Sumter had emerged at Pensacola, Florida, where Confederates threatened another U.S. fortification — Fort Pickens. Lincoln and his new cabinet struggled with the decisions of whether to reinforce the forts, and how. They were also concerned about whether to take actions that might start open hostilities and which side would be perceived as the aggressor as a result. Similar discussions and concerns were occurring in the Confederacy.
After the formation of the Confederate States of America in early February, there was some debate among the secessionists whether the capture of the fort was rightly a matter for South Carolina or for the newly declared national government in Montgomery, Alabama. South Carolina Governor Pickens was among the states’ rights advocates who thought that all property in Charleston Harbor had reverted to South Carolina upon that state’s secession as an independent commonwealth.
The South sent delegations to Washington, D.C. and, offered to pay for the Federal properties and enter into a peace treaty with the United States. Lincoln rejected any negotiations with the Confederate agents because he did not consider the Confederacy a legitimate nation and making any treaty with it would be tantamount to recognition of it as a sovereign government.
On April 6, Lincoln notified Governor Pickens that “an attempt will be made to supply Fort Sumter with provisions only and, that, if such attempt be not resisted, no effort to throw in men, arms or ammunition will be made without further notice, [except] in case of an attack on the fort.”
Lincoln’s notification had been made to the Governor of South Carolina, not the new Confederate Government, which Lincoln did not recognize. Pickens consulted with [P. G. T.] Beauregard, the local Confederate commander. Soon, President Davis ordered Beauregard to repeat the demand for Sumter’s surrender and, if it did not, to reduce the fort before the relief expedition arrived.
Beauregard dispatched aides […] to Fort Sumter on April 11 to issue the ultimatum. Anderson refused, although he reportedly commented, “I shall await the first shot and, if you do not batter us to pieces, we shall be starved out in a few days.”
At 1 a.m. on April 12, the aides brought Anderson a message from Beauregard: “If you will state the time which you will evacuate Fort Sumter, and agree in the meantime that you will not use your guns against us unless ours shall be employed against Fort Sumter, we will abstain from opening fire upon you.”
Maj. Anderson replied that he would evacuate Sumter by noon, April 15, unless he received new orders from his government or additional supplies.
Aide Col. Chesnut considered this reply to be too conditional and [replied] to Anderson: Sir, by authority of Brigadier General Beauregard, commanding the Provisional Forces of the Confederate States, we have the honor to notify you that he will open fire of his batteries on Fort Sumter in one hour from this time.”
Anderson escorted the officers back to their boat, shook hands with each one, and said “If we never meet in this world again, God grant that we may meet in the next.”
Although the Union garrison returned fire, they were significantly outgunned and, after 34 hours, Major Anderson agreed to evacuate. There were no deaths on either side as a direct result of this engagement, although a gun explosion during the surrender ceremonies on April 14 caused two Union deaths.
From Son of the South:
The fort had been evacuated, not surrendered. Anderson bore away the flag of Sumter, which was used as his winding-sheet, and was buried with him.
More reading on The Bombardment of Fort Sumter from Harper’s Weekly, April 27, 1861.