In February 1862, Union forces under Brig. Gen. Ulysses S. Grant captured Forts Henry and Donelson, opening the way into Tennessee. Grant's army moved to Pittsburg Landing on the Tennessee River in preparation for an offensive on Corinth, Mississippi. On April 6, Confederates under Albert Sidney Johnston attacked. Despite the loss of Johnston, the Confederates overran the Union camps and pushed Grant back to the landing. Grant's counterattacked on April and the Confederates withdrew to Corinth.