After the publication of "Captain Sam Grant" (1950) by historian and biographer Lloyd Lewis, Catton wrote the second and third volumes of this trilogy, making extensive use of Lewis's historical research, provided by his widow, Kathryn Lewis, who personally selected Catton to continue her husband's work. In "Grant Moves South" (1960), Catton discussed the increasing experience of Grant as a military commander, from victories at the Battle of Fort Henry and the Battle of Fort Donelson, to the Battle of Shiloh and the Vicksburg Campaign. In "Grant Takes Command" (1969), Catton discussed Grant's career from the Battle of Chattanooga (1863) through the 1864 Virginia campaigns against Robert E. Lee and the end of the war.