The Tennessee River was of vital strategic importance to both sides during the war, and in the spring of 1862 the Union army under Gen. Ulysses S. Grant took control of the river as far south as Pickwick Landing. Grant made his headquarters a few miles north at Savannah and directed his army to gather at nearby Pittsburg Landing, where riverboats could deliver supplies and reinforcements. On April 3, Grant's army arrived at Pittsburg Landing, established its primary base on a plateau west of the river, and placed forward camps two miles inland near Shiloh Meeting House in preparation to attack Confederate Gen. Albert Sidney Johnston's army at Corinth, Mississippi, about 22 miles away. On the morning of April 6, Johnston surprised Grant's troops with an attack that routed most of the forward camps and pushed the rest of the Union army to the river. A decisive Confederate victory seemed imminent, but several Union units held their ground and formed a defensive line along the plateau. After a bullet struck Johnston and he soon died from his wounds, Gen. P.G.T. Beauregard took command. The Confederate charge stalled, and as night came, gunboats and Gen. Don Carlos Buell's command arrived to reinforce Grant. The next day, Beauregard launched a new attack that at first seemed successful, but a Federal counterattack then pushed the Confederates from the battlefield. Grant's and Buell's troops, bloodied from two days of fighting, did not follow up, and the Confederates retreated to Corinth.