The bloody two-day battle of Shiloh changed the course of the American Civil War. The conflagration at Shiloh had its roots in the strong Union advance that resulted in the capture of Forts Henry and Donelson in Tennessee. The offensive collapsed General Albert S. Johnston's advanced line in Kentucky and forced him to withdraw to northern Mississippi. Anxious to attack the enemy, Johnston began concentrating Southern forces at Corinth, a major railroad center just below the Tennessee border. His bold plan called for his Army of the Mississippi to march north and destroy General Grant's Army of the Tennessee before it could link up with another Union army on the way to join him. Johnston's sweeping attack hit the unsuspecting Federal camps at Pittsburg Landing and routed the enemy from position after position as they fell back toward the Tennessee River. Johnston's sudden death in the Peach Orchard, however, coupled with stubborn Federal resistance, widespread confusion, and Grant's determination to hold the field, saved the Union army from destruction. The arrival of General Don C. Buell's reinforcements that night turned the tide of battle. The next day, Grant seized the initiative and attacked the Confederates, driving them from the field. Shiloh was one of the bloodiest battles of the entire war, with nearly 24,000 men killed, wounded, and missing.