Robert Bartley and his Civil War tentmates

    Robert Bartley’s daughter talked many times about his service in the Civil War (on the Union side).  She said he enlisted in the Navy, serving on the Western World, and after his discharge in 1863 enlisted in the 39th Maine Volunteers (Infantry).  He and his infantry tentmates were photographed in December 1864.  Pictured are Capt. Francis Frye (upper left), Sergeant Arthur Hinckley (upper right), Charles Williams (lower left), and Robert Bartley (lower right).   
    There has been quite a bit written about the Western World and its battles, and Robert received a pension for three years service in the Navy, mostly on this ship.  In his Declaration for Pension, he stated that he had also served in the 1st Maine Sharp Shooters Volunteers for eight months, and his obituary mentioned his service with the 39th Maine Volunteer Infantry Regiment.  I have been unable to find any record of his service in either Maine unit. 
    Robert’s daughter noted on the back of the photo that Francis Frye, a tall Maine man, was U .S. Consul to Honolulu after the war; Sergeant Hinckley, stoutish and jolly looking, was killed in action, possible at the Battle of Seven Oaks in Virginia, by a piece of shell that lodged in his heart after passing through Robert’s upper arm; and Charles Williams “was said to have deserted from the Army.”  Robert (1843-1924) was from New York City.  He married, fathered eight children, and worked as a shipping clerk.
    I have been unable to determine the unit these men were in and to verify the comments about Robert's comrades.  Maine’s “Civil War Soldiers and Sailors Card Index, 1861-1865,” does not include anyone who could be one of these men, save for Charles A. Williams from Auburn, who enlisted in Augusta 29 December 1864 in Company D, C.G. Infantry, and deserted 12 January 1865.  That he is the man in the photograph has not been proved.
    Does anyone have information about the soldiers in the photo? 

Sources:
    “Maine, Civil War military rolls, Maine Volunteers, 1861-1865,” index and digital images, FamilySearch
    Robert Bartley’s pension file
Photograph from Buffalogen’s collection