In his inaugural address, Lincoln attempted to be both firm and conciliatory. He declared secession to be wrong; but he also promised that he would "not interfere with the institution of slavery where it exists." He announced that he would use "the power confided to me...to hold, occupy, and possess the property and places belonging to the Government." But he assured Southerners that "there would be no invasion, no using of force against or among the people anywhere."

When he delivered his inaugural address, the new President assumed that there was time for southern pro-union sentiment, which he greatly overestimated, to reassert itself, making a peaceful resolution to the crisis possible. The next morning, however, he received a letter from Robert Anderson informing him that Fort Sumter's supplies would be exhausted in four to six weeks and that it would take a 20,000-man force to reinforce the fort.

Lincoln received conflicting advice about what to do. Winfield Scott, his commanding general, saw "no alternative to surrender," convinced that it would take eight months to prepare naval and ground forces to relieve Fort Sumter. Secretary of State William H. Seward also favored abandoning the fort to avoid provoking a civil war, but also considered the possibility of inciting a foreign war (probably with France or Spain) as a way to reunite the country. Lincoln's Postmaster General Montgomery Blair and Treasury Secretary Salmon P. Chase favored dispatching a force of warships and transports to relieve the fort and assert federal authority, since "every hour of acquiescence ... strengthens [the rebels'] hands at home and their claims to recognition as an independent people abroad."

In the end, Lincoln decided to try to peacefully re-supply the fort with provisions and to inform the Confederate government of his decision beforehand. Unarmed ships with supplies would try to relieve the fort. Only if the South Carolinians used force to stop the mission would warships, positioned outside Charleston harbor, go into action. In this way, Lincoln hoped to make the Confederacy responsible for starting a war.

Upon learning of Lincoln's plan, Jefferson Davis ordered General Pierre G.T. Beauregard (1818-1893) to force Fort Sumter's surrender before the supply mission could arrive. At 4:30 a.m. April 12, Confederate guns began firing on Fort Sumter. Thirty-three hours later, the installation surrendered. Incredibly, there were no fatalities on their side.

Ironically, the only fatalities at Fort Sumter occurred just after the battle ended. During the surrender ceremony, a pile of cartridges ignited, killing one soldier, fatally wounding another, and injuring four.