The Demon of Unrest by Erik Larson is a really good work of nonfiction subtitled A Saga of Hubris, Heartbreak, and Heroism at the Dawn of the Civil War. Larson delves into the period prior to the war and the specific events at Fort Sumter, on an island in the harbor just off the shores of Charleston, SC.
It's fascinating how Larson takes a large event and then focuses on a specific thing that helped bring it about. The lobbing of munitions at U.S. military personal at Fort Sumter by forces of South Carolina, who had announced a succession from the Union, could be considered a powder keg prior to the blast that was the Civil War, which would kill 750,000 Americans.
Lincoln won the presidential election on Nov 6, 1860, enraging southerners who felt that Lincoln wanted to end slavery, taking away the forced labor that harvested their cotton. The results of the election triggered people to align themselves with either the government of the U.S. or those who wanted to continue slavery. South Carolina led the charge to succeed, holding first a session of the legislature on Nov 10 about whether to leave the Union, and then a succession convention at the start of January. Mississippi then joined in succeeding on Jan 9, again due to slavery.
The certification of Electoral College votes was Feb 13, and leading up to it, there was concern that there would be disruption from people who didn't want Lincoln in office, and inauguration was Mar 4, with there rumors of planned assassination attempts on Lincoln while on the way to Washington. The outgoing president, James Buchanan, had hoped that Lincoln would be defeated in the presidential race, as he simply wanted to harmony before leaving his responsibilities. Lincoln's speeches leading up to his assuming office were critical as people wanted to know what he would do both about slavery and the states wanting out of the Union.
During this time, Major Robert Anderson in South Carolina consolidated U.S. forces from other forts around Charleston Harbor into Fort Sumter, an action viewed as an affront by those in Charleston as the state declared itself outside the government. South Carolina began making preparations to attack the fort if Anderson wouldn't abandon and hand it over to them. When Lincoln was sworn into office, Anderson had been at Fort Sumter some three months and he others there had dwindling provisions and not a great deal of guidance, much less timely guidance, coming to them from Washington. Confederate President Jefferson Davis wanted to be done with the American flag flying from Fort Sumter in view of Charleston and on the April 12, 1861 day that artillery was lobbed at Fort Sumter, Anderson had been there for 113 days. The bombardment caused a fire, compelling Anderson to surrender the fort and evacuate with his men.
Many people in the South thought this was all a grand adventure, one that would be over quickly, but Lincoln responded by calling for troops to assemble to reassert the authority of U.S. law, and the war commenced. Four years later the U.S. retook Fort Sumter, with the Civil War killing a full third of the 60,000 men in the state who fought. Also, the war brought what southerners feared, the end of slavery cost South Carolina planters some three hundred million dollars in human capital. Larson does a great job in the book of detailing this specific place and event at the start of a conflict that wound up killing a quarter of a million people, and all the sliding door moments that led up to the Civil War.