On April 2nd, 1863, Major General Oliver O. Howard replaced Franz Sigel in command of the 11th Corps after Sigel resigned due to poor health. On April 20th, Brigadier General Charles Devens replaced a very unhappy Brig, Gen. McLean who returned to his brigade. Devens, who was a strict disciplinarian and a bit of a snob, felt that he had been brought in to bring this "Dutch" mob "up to snuff". He quickly rubbed everyone the wrong way and morale took a slump.At this time the composition of McLean's brigade changed. It now consisted of the 17th Connecticut, 25th Ohio, 55th Ohio, 75th Ohio and the 107th Ohio. The 55th was still commanded by Col. John Lee and Lt. Col. Charles Gambee.
The Chancellorsville Campaign commenced on April 27th, 1863. The 11th Corps began to march up the Rappahannock River in Virginia towards Kelly's Ford, crossing that place on April 30th.
Sources:
Trials and Triumphs: A Record of the Fifty-Fifth Ohio Volunteer Infantry by Hartwell Osborne, 1904, A.C. Clurg & Co., Chicago.
All Brave And True by Dan Munson, 1987.