Explain the key events and importance of the Battle of Shiloh?

Grant lead the Union forces down the Mississippi River and stopped just before Memphis. Then he took his forces down the Tennessee River and prepared to push into Mississippi to cut one of the major east-west railroads. The Confederates planned a surprise attack to push them back and hopefully regain control of West Tennessee. The battle started with the Rebels surprise attack while the Yanks were still eating breakfast in their camps. The Rebels had the initiative until their leader was killed. Grant established a strong line of defense at the banks of the river called Pittsburg Landing. He sent Word for Buell's army to come to his assistance. They marched over land and arrived the first evening and used the river boats to cross the Tennessee River. The 2nd day, Grant's forces took the offensive and pushed the Rebels slowly back to the original starting position. The loss of Shiloh meant the Confederates had to give up their possession of West Tennessee. It started Grant on his advance through northern Mississippi that culminated in the Battle of Vicksburg and the defeat of the major army in Mississippi.