His plans and decisions proved extremely effective in the Western Virginia Campaign. His victories at Rich Mountain and Corrick's Ford in July 1861 were among the first Union victories of the war, but his superior, Maj. Gen. McClellan, received the credit. Rosecrans then prevented, by "much maneuvering but little fighting," Confederate Brig. Gen. John B. Floyd and his superior, Gen. Robert E. Lee, from recapturing the area that became the state of West Virginia. When McClellan was summoned to Washington after the defeat suffered by Federal forces at the First Battle of Bull Run, General-in-Chief Winfield Scott suggested that McClellan turn over the West Virginia command to Rosecrans. McClellan agreed, and Rosecrans assumed command of what was to become the Department of Western Virginia.