April 12, 1861: The American Civil War begins.
Only two months after the Confederate States of America was formed, the inevitable battle over the legitimacy of secession began when Confederate forces under P.G.T. Beauregard began to bombard Union-held Fort Sumter. Although bombardment by the Confederates lasted for hours, not one man on either side was killed. However, two men - Privates Daniel Hough and Edward Gallway - became the first casualties of the American Civil War when they were killed as the surrendering Union forces performed a 100-gun salute to their flag.
Although relatively bloodless and peaceably resolved, the Battle of Fort Sumter and the subsequent Union surrender riled up Northerners, who offered themselves up by the thousands to Lincoln’s call for volunteer troops. Southern states that had up until now remained in the Union responded with outrage as well - at Lincoln, that is. They denounced his recruitment of troops as preparation for an “unholy crusade” to “[subdue] her sister Southern states”. The vital state of Virginia seceded from the Union only a few days after Fort Sumter, taking with it Colonel Robert E. Lee,who ensured that this would-be small rebellion dragged on for four long years.