This photograph shows Lieutenant-Colonel Hallewell and a servant at the end of the day. The royal photographer Roger Fenton (1819–1869) made a series of portraits of the British general staff, who resided in comfort far from the front.
Roger Fenton (1819–1869), Lieutenant-Colonel Hallewell Relaxing after the Day, collodion photograph, 1854; source: courtesy of George Eastman House, International Museum of Photography and Film, https://collections.eastman.org/objects/273873/lieutenant-colonel-hallewell-his-days-work-over?ctx=5f97d9fe-1586-4f31-a098-7e0ee5d4a0ed&idx=0.