Battle of Shiloh
In Mississipi, the Battle of Shiloh commenced when General Johnston moved his Confederate forces near the Tennessee border. Grant was moving his army south along the Tennessee River but later exposed the 42,000 troops to a valley in between two higher Confederate-occupied grounds. Johnston led a surprise attack on Grant's troops and many were killed in the Union camp. However, the Confederacy gave up a victory when Johnston was mortally wounded in battle and his second-in-command called off the offensive attack. By the time Grant's army was on the offensive and drove the rebels out, deaths on either side amounted to over 20,000. It was to be the costliest battle in the war until Gettysburg.