On November 11, 1864, having sent General George Thomas to Nashville with the 4th and 23rd Corps to defend against Hood's invasion of Tennessee, General W. T. Sherman restructured his remaining force into two "wings". the "Left Wing", composed of the 14th and 20th Corps, was given to General Henry Slocum. Brigadier General Alpheus Williams assumed command of the 20th Corps. Slocum's men quickly adopted the title "Army of Georgia", which was officially recognized on March 28, 1865.
On November 15th, the 55th Ohio, with the rest of the 20th Corps, departed Atlanta as Sherman began his "March to the Sea" campaign towards Savannah, Georgia. The corps was directed originally along the rail line leading from Atlanta to Augusta as a diversion to confuse the enemy as to Sherman's real goal. The men engaged in railroad destruction as they went along. By the 23rd of the month, having turned his men southward after passing Madison, Slocum's "wing" linked with Howard's forces (15th and 17th Crops) at Milledgeville, the state capitol of Georgia.
On the 25th of November, Sherman's united force set out from Milledgeville, bound for Savannah. Marching virtually unopposed, save for several cavalry skirmishes and one small infantry affair at Griswoldsville, the "March to the Sea" left a swath of destruction 60 miles wide. It was described more as a "military picnic" than a campaign.
Sources Trials and Triumphs by Hartwell Osborne, 1904
All Brave and True by Dan Munson, 1986