Born at Portsmouth in 1867, the younger son of William Marshall, solicitor, Southsea. He studied at University College Hospital, where he was House Surgeon and Demonstrator of Anatomy. At the Royal London Ophthalmic Hospital, City Road (formerly Moorfields), he was House Surgeon, Clinical Assistant, Curator of the Museum, Librarian, and in 1902 was appointed Surgeon. In that connection he acquired a great reputation for scientific knowledge and skill; a good teacher and lecturer, he built up a practice at 112 Harley Street. Besides, he was Ophthalmic Surgeon to the Victoria Hospital for Children, Chelsea, from 1899, and to the Royal Society of Musicians. At the Ipswich Meeting of the British Medical Association in 1900 he was Secretary of the Section of Ophthalmology, and Vice-President of the same Section at the Sheffield Meeting in 1908. He made numerous communications on ophthalmology, especially in the *Royal Ophthalmic Hospital Reports*, and published *Researches on Colour Vision* in collaboration with F Edridge Green, which included an experiment on the diffusion of visual purple into the fovea. His small book for students, *Diseases of the Eye*, 1912, was referred to as "probably the best that has been written for the general practitioner" - "most lucid". The same applies to the article "Diseases of the Eye" in Power and Murphy's *System of Syphilis*. An enthusiastic yachtsman, he sailed his own yacht for many years, and joined the London Division of the Royal Naval Reserve in 1903; was promoted Lieutenant in 1906, and transferred to the Medical Branch in 1909. He joined HMS *Euryalus* at Chatham at the outbreak of the War, August 2nd, 1914. In this ship he was present at the Battle of Heligoland Bight, and for some months after in the defence of home waters. He next served on the Flagship in the Mediterranean, was present at the Suvla Bay landing in 1915 and throughout the Gallipoli operations up to the evacuation. He was promoted Staff Surgeon in 1916, and a colleague wrote of him:- "I have never met any man who so completely won the esteem and affection of everyone in his ship. It was to Marshall we naturally turned when down on our luck. His religious convictions influenced his whole life he was a tender- hearted doctor he loved his life at sea; he was father and mother to every youngster on board. On that ghastly night following the landing at Gallipoli he heard that an attempt was to be made to evacuate the wounded from the River Clyde, which was at the time aground and under musketry fire from both sides. Although he had been continuously at work for eighteen hours he at once volunteered and went." In 1917 he was appointed Principal Medical Officer in the Persian Guff and Mesopotamia, was present at some of the Mesopotamian operations, and went up the Tigris in the river gunboats as far as Bagdad. He was serving on HMS *Dalhousie* when he died of cholera in the Isolation Hospital, Bombay, on September 14th, 1918. His name is on the College Roll of Honour.