Johnston concentrated many of his forces from around the theater and launched a massive surprise attack against Grant at the
Battle of Shiloh on
April 6, 1862. As the Confederate forces overran the Union camps, Johnston seemed to be everywhere, personally leading and rallying troops up and down the line. At about 2:30 p.m., while leading one of those charges, he was wounded, taking a bullet behind his right knee. He did not think the wound serious at the time, and sent his personal physician to attend to some wounded Union soldiers instead. The bullet had in fact clipped his
popliteal artery and his boot was filling up with blood. Within a few minutes Johnston was observed by his staff to be nearly fainting off of his horse, and asked him if he was wounded, to which he replied "Yes, and I fear seriously." It is possible that Johnston's duel in 1837 had caused nerve damage or numbness to that leg and that he did not feel the wound to his leg as a result. Johnston was taken to a small ravine, where he bled to death in minutes.
It is probable that a Confederate soldier fired the fatal round. No Union soldiers were observed to have ever gotten behind Johnston during the fatal charge, while it is known that many Confederates were firing at the Union lines while Johnston charged well in advance of his soldiers. He was the highest-ranking casualty of the war and his death was a strong blow to the morale of the Confederacy. Jefferson Davis considered him the best general in the country; this was two months before the emergence of
Robert E. Lee as the pre-eminent general of the Confederacy.