Arthur Mercer Davies was the son of the Rev Mercer Davies. He was educated at Queen's College Cork and at Westminster Hospital taking the LSA in 1879 the MRCS in 1880 and subsequently the DPH at Cambridge in 1889.
30 July 1881 Entered the army as Surgeon-Captain.
1882-84 Served in the Egyptian Campaign (13 July–13 Sept 1882). He received the Medal and the Bronze Star. He was present at the battles of Teb and Tamai in 1884 receiving the two clasps and the clasp for the Nile in the Sudan Expedition of 1884-85.
The threat to the route to India via the Suez canal, which opened in 1869, mismanagement of Egypt's financial affairs by its ruler the Khedive Ismail Pasha, and a popular nationalist uprising by Ahmad Urabi Pasha Al–Misri, led to the dispatch of an Expeditionary Force under the command of Lieutenant–General Sir Garnet Wolseley to stabilise the country. The Egyptians were defeated in the Battle of Tel–el–Kebir on 13 Sept 1882, and Britain took control of Egypt.
1884–1885 Served in the Sudan.
Possession of Egypt gave Britain responsibility for the Egyptian empire to the south in Sudan. Continued turbulence and unrest, eventually led to Britain's withdrawal from Sudan in 1896.
1886–1892 Assistant Professor of Military Hygiene, Army Medical School Netley.
30 July 1893 Surgeon-Major.
30 July 1901 Lieutenant Colonel RAMC.
Malta 19 May 1905 Arrived at Malta as part of The Mediterranean Fever Commission 1904–1906.
The members of the Mediterranean Fever Commission, 1904 were: Major William Horrocks RAMC, Staff–Surgeon Ernest Shaw RN, Dr Themistocles Zammit, Dr Ralph Johnstone, Captain James Crawford Kennedy RAMC, and Staff-Surgeon Ernest Gilmour RN
7 Oct 1905 Returned to England.
1 Feb 1906–1908 Professor of Hygiene Royal Army Medical College Millbank.
7 June 1907 Highly commended by the Royal Society for services rendered in connection with the investigations into the causes of Mediterranean Fever.
17 Sept 1908 Retired. Post retirement was medical assistant in the Public Health Department of the London County Council.
He was author of a standard Handbook of Hygiene, and The Food of the Soldier (1889) and a large number of official reports and contributions to the Medical Press chiefly on subjects connected with Public Health, Military Hygiene and Bacteriology
- Entry No: 6858. Johnston W. Roll of Commissioned Offices in the Medical Service of the British Army. Vol 1 (20 June 1727-23 June 1898). Aberdeen (1917).
- Distribution of RAMC Officers. Corps News Vol IV: 6; June 1905.
- Succession Books Vol XVI, Returns of statement of service of RAMC Officers.
- Deaths in the Services, Br Med J (1929), 936 (Published 29 November 1929).