Encamped with 40,000 men at Pittsburg Landing on the Tennessee River, General Grant awaited Buell's reinforcements before moving on Corinth, Mississippi. A.S. Johnston's Confederates surprised them at breakfast by attacking near Shiloh Church, driving in the pickets and pushing the whole force back 2 miles, almost to the River. Grant's personal intervention along with a spirited last stand of Prentiss' division and Union gunboats' artillery stopped the advance by late evening on the 6th. Johnston himself was killed leading an attack. During the night Buell's advance units arrived and crossed the river and the Union counter attack drove the Confederates back to Corinth.
The huge casualty figures of around 20,000 at Shiloh eclipsed anything seen so far during the war, and set the pattern for the next three years.