Grant, supported by Buell's Army of the Ohio and a division under Major General Lewis “Lew” Wallace, defeats Confederate forces under General Beauregard at Shiloh (Pittsburg Landing), Tennessee, in the struggle for control of the Upper Mississippi.

On the second day of the Battle of Shiloh, April 7, Grant receives reinforcements from Buell and launched a counterattack that drives back the Confederates.

Grant fails to pursue the retreating enemy and will receive enormous criticism for this and for the great loss of life—more casualties (almost twenty-four thousand) than all previous American battles combined on the Battle of Shiloh.

Although the 61,681 Union troops far outnumbered the 40,335 Confederates, the casualties on both sides are relatively equal.

The Union ranks suffer 1,754 killed, 8,408 wounded, and 2,885 missing, while the Confederates list 1,773 killed, 8,012 wounded, and 959 missing.