The Battle of Shiloh (aka Battle of Pittsburg Landing) was the first major battle in the Western Theatre of the American Civil War and the bloodiest battle in United States history up to that time. A two-day affair (April 6-7, 1862), the Confederates appeared to be on their way to a major victory after the first day of action, but Union reinforcements counterattacked the next day, driving the defeated Confederates from the field. The bloody fighting at the infamous "hornet's nest"--where bullets flew as thick as hornets--was an example of the old European style warfare: Instead of bypassing the heavily fortified Union position, the Confederates stubbornly assaulted it more than a dozen times before assembling 50 cannon to blast the surviving Union troops from the position.
In the aftermath of the battle, both sides were stunned at the carnage and high casualty rates; combined total casualities totalled nearly 24,000, including Confederate General Albert Sydney Johnston, considered the South's finest commander. Few people in either the North or South thought the war would last but a few months, but Shiloh changed the opinions of many. The battle also introduced the nation to two men who would become the finest commanders in the Union army by the end of the war: Ulysses S. Grant and William Tecumseh Sherman.