The Battle of Shiloh, also known as the Battle of Pittsburg Landing, was a major battle in the Western Theater of the American Civil War, fought April 6-7, 1862, in southwestern Tennessee. A Union army under Major General Ulysses S. Grant had moved via the Tennessee River deep into Tennessee and was encamped principally at Pittsburg Landing on the west bank of the river, where Confederate forces under Generals Albert Sidney Johnston and Pierre G. T. Beauregard launched a surprise attack on Grant's army. Johnston was killed in action during the fighting; Beauregard, who thus succeeded to command of the army, decided against pressing the attack late in the evening. Overnight Grant received considerable reinforcements from another Union army under Maj. Gen.