The first half of 1862 was disastrous for the Confederate army in the West. Beginning with Forts Henry and Donelson in February, the South suffered one defeat after another. An entire field army of some fifteen thousand men surrendered at Fort Donelson, leading to the collapse of Confederate defenses in southern Kentucky and western and central Tennessee. That vast area, with its rich storehouse of goods and agricultural products, was laid open to the Yankee invaders. The Federal offensive temporarily came to a halt at Shiloh when the Army of the Mississippi under Gen. Albert Sidney Johnston surprised the Army of the Tennessee under Maj. Gen. Ulysses S. Grant in its camps on a peaceful spring morning. The fighting that day, April 6, 1862, was fierce and bloody, but Grant's troops blunted the Confederate attacks and held their forward base of supplies at Pittsburg Landing on the Tennessee River. Grant was joined that night by the Army of the Ohio under Maj. Gen. Don Carlos Buell. Together, the two Federal armies drove the outnumbered Rebels away. Johnston was killed, shot accidentally by his own men, on April 6. Now led by Gen. Pierre G. T. Beauregard, the Army of the Mississippi retreated safely back to Corinth. The Rebels failed to crush Grant or prevent his juncture with Buell and had suffered nearly twelve thousand casualties, but they put almost thirteen thousand Federal troops out of action in the two-day battle.
Reinforcements from the Trans-Mississippi and new regiments from the North enabled Grant and Buell to hold the strategic advantage. But they would not be given the opportunity to continue the advance toward Corinth on their own. Their superior, Maj. Gen. Henry Wager Halleck, hastened to take personal charge of their combined armies, which numbered over one hundred thousand men. Not until the Atlanta campaign of 1864 would the