The Battle of Fort Sumter (April 12–14, 1861) was the bombardment and surrender of Fort Sumter, near Charleston, South Carolina, that started the American Civil War. Following declarations of secession by seven Southern states, South Carolina demanded that the US Army abandon its facilities in Charleston Harbor. On December 26, 1860, Major Robert Anderson of the U.S. Army surreptitiously moved his small command from the vulnerable Fort Moultrie on Sullivan's Island to Fort Sumter, a substantial fortress controlling the entrance of Charleston Harbor. An attempt by U.S. President James Buchanan to reinforce and resupply Anderson, using the unarmed merchant ship Star of the West, failed when it was fired upon by shore batteries on January 9, 1861. South Carolina authorities then seized all Federal property in the Charleston area, except for Fort Sumter.

Warfare in the Eastern theater started poorly for the Union as the Confederates won at Manassas Junction (Bull Run), just outside Washington. Major General George B. McClellan was put in charge of the Union armies. After reorganizing the new Army of the Potomac, McClellan failed to capture the Confederate capital of Richmond, Virginia in his Peninsula Campaign and retreated after attacks from newly appointed Confederate General Robert E. Lee.Feeling confident in his army after defeating the Union at Second Bull Run, Lee embarked on an invasion of the north that was stopped by McClellan at the bloody Battle of Antietam. Despite this, McClellan was relieved from command for refusing to pursue Lee's crippled army. The next commander, General Ambrose Burnside, suffered a humiliating defeat by Lee's smaller army at the Battle of Fredericksburg late in 1862, causing yet another change in commanders. Lee won again at the Battle of Chancellorsville in May 1863, while losing his top aide, Stonewall Jackson. But Lee pushed too hard and ignored the Union threat in the west. Lee invaded Pennsylvania in search of supplies and to cause war weariness in the North. In perhaps the turning point of the war, Lee's army was badly beaten at the Battle of Gettysburg, July 1–3, 1863, and barely made it back to Virginia.Simultaneously on July 4, 1863, Union forces under the command of General Ulysses S. Grant gained control of the Mississippi River at the Battle of Vicksburg, thereby splitting the Confederacy. Lincoln made General Grant commander of all Union armies.

Battle of Franklin, November 30, 1864

The last two years of the war were bloody for both sides, with Grant launching a war of attrition against General Lee'sArmy of Northern Virginia. This war of attrition was divided into three main campaigns. The first of these, the Overland Campaign forced Lee to retreat into the city of Petersburg where Grant launched his second major offensive, theRichmond-Petersburg Campaign in which he besieged Petersburg. After a near ten-month siege, Petersburg surrendered. However, the defense of Fort Gregg allowed Lee to move his army out of Petersburg. Grant pursued and launched the
final, Appomattox Campaign which resulted in Lee surrendering his Army of Northern Virginia on April 9, 1865, at Appomattox Court House. Other Confederate armies followed suit and the war ended with no postwar insurgency.

Based on 1860 census figures, about 8% of all white males aged 13 to 43 died in the war, including 6% from the North and 18% from the South,establishing the American Civil War as the deadliest war in American history. Its legacy includes ending slavery in the United States, restoring the Union, and strengthening the role of the federal government.