The Battle of Shiloh was a battle in the Western Theater fought April 6–7, 1862, in southwestern Tennessee. On the first morning, 40,000 Confederate troops struck Union Soldiers at Pittsburg Landing. They were under the command of Major General Ulysses S. Grant. The Confederate Army of Mississippi, under the command of General Albert Sidney Johnston, launched a surprise attack on Grant's army from its base in Corinth, Mississippi. Johnston was mortally wounded during the fighting; Beauregard took command of the army and decided against pressing the attack late in the evening. Overnight, Grant was reinforced by one of his divisions stationed further north and was joined by three divisions. The Union forces began an counterattack the next morning which reversed the Confederate gains of the previous day.