In July 1862, Lincoln summoned Henry Halleck to Washington to serve as general-in-chief; Halleck was not replaced as departmental commander, leading by September to the demise of the geographically broad Department of the Mississippi. One immediate result was that, on July 16, Halleck enlarged Grant's District of West Tennessee and included within it portions of Alabama and Mississippi, as well as the Army of the Mississippi, five divisions then under the command of Maj. Gen. William S. Rosecrans. Grant relocated his headquarters to Corinth (and later Jackson, Tennessee) to oversee his expanded responsibilities. He soon lost four divisions from this expanded command—that of George Thomas and three from Rosecrans's Army of the Mississippi—to Buell's Army of the Ohio; these losses shrank Grant's forces from approximately 80,000 men to less than 50,000. This threw Grant on the "defensive," simply trying to deploy his remaining forces to protect his own positions against threatening Confederate forces; Grant later described this as his "most anxious period of the war." It came to an end with victories led by General Rosecrans in the September Battle of Iuka and the more consequential October Battle of Corinth. Grant was nearby and coordinating with Rosecrans, but not on the field, for these two battles; Rosecrans fought Iuka with elements of his shrunken Army of the Mississippi, and Corinth with the addition of two divisions from the Army of the Tennessee. The victory at Corinth was sufficiently clear cut to relieve Grant "from any further anxiety for the safety of the territory within my jurisdiction."