Born on 18 January 1868 in Cornwall the son of Captain Henry Rogers RN, he was educated at Plymouth College and St Mary's Hospital where he passed the final examination for the Fellowship at the age of 24 while holding the post of resident obstetric officer. He then entered the Indian Medical Service being gazetted Lieutenant on 29 July 1893, his subsequent promotions being to Captain in 1896, to Major in 1905, Lieutenant-Colonel in 1913 and he retired in that rank in 1921. He was, however, immediately appointed to the Medical Board of the India Office on which he served for twelve years being its President in 1928-33 and being promoted Major-General on 3 November 1928. As he himself said he joined the IMS "solely in the hope of finding better opportunities for research when there were few openings in Great Britain", and again "I fear I made little use of the Fellowship except as having been the first to diagnose and operate on biliary abscesses of the liver in 1903 in Calcutta". A dedicated research worker he did, however, in the course of his regimental duties in various parts of India, demonstrate his abilities as an all-round clinician and public health administrator before devoting himself exclusively to research work. As Professor of Pathology in the Medical College in Calcutta he took the initiative in founding and endowing the School of Tropical Medicine which stands in Calcutta as a permanent memorial to his name. Although his work on cholera, amoebic dysentery and kala-azar saved many, he was proudest at having galvanised interest in leprosy by founding the British Empire Leprosy Relief Association in 1923, he himself having for many years been interested and having devised many improvements in the methods of using chaulmoogra oil in its treatment. In the late nineties he commenced research on snake venom and, in the course of hazardous experiments into its nature, improved the methods of production of antivenene. In 1904, by a brilliant piece of work carried out at the research station at Maktesar near Naini Tal in the Himalayan foothills, he predicted the development of Leishman Donovan bodies outside the blood of man, although he had been forestalled by those two workers in the actual discovery of the parasite of kala-azar in 1903. He next turned his attention to cholera and he proved that the mortality could be substantially reduced by intravenous hypertonic saline and oral potassium permanganate, travelling to Palermo in 1911 to test out his methods in a great epidemic raging in that city. In 1912 he discovered the curative action of emetine in amoebic dysentery and in 1915 made another advance by discovering the use of intravenous tartar emetic in the treatment of kala-azar. On his return to England he was appointed a physician to the Hospital for Tropical Disease and lecturer to the London School of Hygiene and Tropical Medicine. Numerous honours and distinctions were awarded him and he had already in 1916 been elected a Fellow of the Royal Society. In 1924 he was Croonian lecturer at the College of Physicians and his distinctions included the Moxon Gold Medal of that College, the Fothergill Gold Medal of the Medical Society of London, the Presidency of the Royal Society of Tropical Medicine and Hygiene from 1933 to 1935, the Laveran Medal in 1956 and honorary membership of the Cambridge Philosophical Society. A prolific writer he published numerous papers and textbooks including one on *Tropical Medicine* in conjunction with Major-General Sir John Megaw, a friend and contemporary, a book on *Dysentery and Bowel Disease in the Tropics* and one on *Leprosy* in conjunction with E Muir. He retained his interest in tropical disease into advanced old age and contributed articles from his home in Cornwall, bombarding younger colleagues with technical advice on medical and financial matters. In 1926 he had entrusted the Medical Research Council with an endowment for research in tropical medicine and in 1945 he raised this to fifteen thousand pounds. A staunch upholder of the Research Defence Society, he was prepared to mount a soap box in Hyde Park in answer to the anti-vivisectionists. In 1950 he published his fascinating and modest memoirs *Happy Toil* (Frederick Muller 1950), which was at first refused by the publishers on the grounds that it was quite impossible for one man to have done so much. In 1953 he received the congratulations of the President and Council on having completed sixty years as a Fellow, and in 1958 at the age of 90 The Lancet published his paper on "The Forecasting and Control of Cholera epidemics in SE Asia and China". A forceful, energetic, striking personality, he exerted a memorable influence on his students by whom he was held in great affection. He was, moreover, of a most upright, kindly disposition, ever helpful to his friends. He married in 1914 in his late forties Una Elsie, daughter of C N McIntyre North who died in 1951 and by whom he had three sons, Dr Gordon Leonard Rogers, Professor Claude Ambrose Rogers FRS, Professor of Mathematics in London University, and Dr Stephen Clifford Rogers. He died in Truro Hospital on 16 September 1962 aged 94, the senior Fellow of both Royal Colleges.