The Confederate concentrated their forces for an attack on Grant, to prevent the loss of this vital junction. Grant had been given overall command of Union operations at Pittsburgh Landing on March 17 with 33,000 troops. The Confederates army started marching from Corinth on the afternoon of April 3.5 The Confederates were supposed to be in position to attack by early morning on April 5th. The attack was postponed until early Sunday afternoon, April 6th due to a violent rainstorm that delayed the confederate army from getting into position until the afternoon of April 6th. .
This delay was not very crucial, since Grant had not anticipated an attack, especially after the victory at Fort Donelson.6 General Johnston intended to advance with three corps formed in a column, supported by Reserve Corps under General Breckinridge. But by the time Johnston read Beauregard's changed the battle orders, it was too late since the march was on the way. This shows the breakdown of command and control and plans falling through. Still, Johnston believed the Union forces could not present a larger front between the two creeks surrounding Pittsburgh Landing than his could. The first shot at the battle of Shiloh rang out at 0514 hours. The Union forces were caught utterly unprepared by the shots fired by the Confederate outposts and Peabody's patrol.7 General Grant was not present at the time, but instead waited for General Buell to arrive. The Union division commanders acted on their own initiative, and started moving their troops to the front, an excellent tactic on their part. Thousands of Union troops ran away to take shelter along the Tennessee River, but thousands more stayed to fight. An almost equal amount of Rebel troops turned away or looted abandoned camps, while more pushed on with the attack.
The Union army had a swampy stream, Owl Creek, on its right flank; both of these ran into the Tennessee River.
