 Complete the following phrase:  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 Grants 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 commandthat of George Thomas and three from Rosecranss Army of the Mississippito Buells Army of the Ohio; these losses shrank Grants 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 