Civil War Diary: Sergeant Hassell Hopper, Company E. 101st Regiment, Illinois Volunteer Infantry.
The 101st Illinois Volunteer Infantry was a regiment of the 11th Corps, Army of the Potomac. The 11th and 12th Corps were sent to reinforce The Army of the Cumberland in 1863.
Link to Diary [This link is an automatic PDF download, 74 pages]
Background: The 11th Corps, Army of the Potomac, saw action at Chancellorsville and Gettysburg. In 1863, the 11th and 12th Corps were transferred west to help reinforce Rosecrans' Army of the Cumberland. Rosecrans assigned the two corps to guard the supply line (Murfreesboro, Tennessee, to Bridgeport, Alabama).
Wikipedia article: "XI Corps (Union Army)"
Link to Article
William S. Rosecrans and the Union Victory: A Civil War Biography
David G. Moore
Google Preview of Book, targeted page: 132
11th and 12th Corps mentioned on page 132 (transferred to Army of the Cumberland)
Short URL: http://bit.ly/Rosecrans-src-XI-and-XII-Corps-Potomac-reinforcemt