Halleck's department performed well in early 1862, driving the Confederates from the state of Missouri and advancing into Arkansas. They held all of West Tennessee and half of Middle Tennessee. Grant, not yet aware of the political maneuvering behind his back, regarded Halleck as "one of the greatest men of the age" and Maj. Gen. William T. Sherman described him as the "directing genius" of the events that had given the Union cause such a "tremendous lift" in the previous months. This performance can be attributed to Halleck's strategy, administrative skills, and his good management of resources, and to the excellent execution by his subordinates—Grant, Maj. Gen. Samuel R. Curtis at Pea Ridge, and Maj. Gen. John Pope at Island Number 10. Military historians disagree about Halleck's personal role in providing these victories. Some offer him the credit based on his overall command of the department; others, particularly those viewing his career through the lens of later events, believe that his subordinates were the primary factor.