Photograph of Lieutenant O'Reilly sitting facing partly left with his right arm resting on the table beside him. His left hand is on his knee and a sword rests between his legs. He is wearing full military uniform including medals and insignia. On the table beside him to the left there is a rolled document with a visible label which reads 'FORTIFICATIONS OF SEBASTOPOL, LIEUT. MONTAGU O'REILLY, R.N, H.M.S Retribution, January 6 1851'. During the Crimean War Lieutenant O'Reilly was commissioned by the Admiralty to make a plan of the fortifications of Sevastopol.
