28 Feb 1792 Regimental Mate 20th Regiment of Dragoons.
28 Aug 1793 Hospital Mate St Domingo.
10 June 1795 Surgeon Colonel Keppell's Regiment of Foot.
16 Sept 1795 Surgeon 23rd (Royal Welsh Fusiliers) Regiment of Foot.
18 Nov 1795 Surgeon Staff.
22 Aug 1805 Deputy Inspector of Hospitals.
1808–1809 Served in the Peninsular War.
18 Jan 1816 Appointed Inspector General following the retirement of Inspector of Hospitals James Borland.
13 Feb 1816 General Order from the Director General of the Army Medical Board proposed that: "Mr Warren, the successor to Borland, should make an inspection of the several Mediterranean stations".
Malta 12 Mar 1816 Arrived from England.
Malta Apr 1817 Returned to Malta from an inspection of the Mediterranean Stations.
Malta 1818 Principal Medical Officer Malta and the Ionian Islands.
Malta May 1819 In the Ionian Islands.
Aug 1819 Returned to Malta.
Malta July 1820 Placed on half-pay and struck off the strength of the Malta garrison.
25 Sept 1821 Retired with an allowance of £300 for injury in Service.
1 July 1838 One of twenty two Inspectors General on half pay. Total Service: 46 years 4 months, Total Full Pay Service: 28 years 9 months.