Surgeon Major Robert De Burgh Riordan entered the Army Medical Department as a Staff Assistant Surgeon on 1 October 1860. He served in the Egyptian war of 1882 as Senior Medical Officer with the advanced force which landed at Alexandria in July and was awarded the Egypt medal and Khedive's Bronze Star. He was also present in the Sudan Campaign in 1885, for which he received a clasp.
1 Oct 1860 Appointed Staff Assistant Surgeon.
24 May 1861 In 1861 there was a reduction in the strength of the army and many medical officers were reduced to to half-pay.
14 Jan 1862 Restored to full-pay.
18 Mar 1862 Appointed Assistant Surgeon 38th (1st Staffordshire) Regiment of Foot, following the resignation of Assistant Surgeon Colin Henderson 38th Foot. The subsequent vacancy on the Staff was filled by Assistant Surgeon William Henry Corbett 81st Foot.
Apr 1873 Moved from 38th Foot to the Medical Staff at Dover.
16 June 1873 Played cricket for 38th Foot against 60th Rifles at Folkestone Cricket Club Ground Folkestone.
1873 – 1875 On duty in Aldershot.
30 Sept 1875 Promoted Surgeon Major.
1875 – 1878 On duty in Bermuda.
Jan 1879 Moved from Bermuda to York.
1879 – 1881 On duty in Weedon.
Malta 20 Mar 1881 Arrived from England.
Malta 7 July 1882 Left on the Expedition to Egypt.
24 Aug 1882 Returned to Malta from Egypt.
Malta 6 May 1883 To England on leave.
2 Aug 1883 Returned to Malta.
Malta 1884 On garrison duty.
Malta 20 Apr 1885 To England on leave.
2 July 1885 Returned to Malta.
Malta 13 May 1886 Left for Cork.
July 1886 Moved from Cork to Fermoy.
26 July 1891 Placed on retired pay. Settled in Newcastle on Tyne until his death on 3 December 1894 at the age of 58 years.
- Drew R., 1968. Entry No: 5968. Medical Officers in the British Army 1660 – 1960. Volume 1: 1660 – 1898. London: Wellcome Historical Medical Library.
- RAMC/PE/3/27/Drew. Manuscript for Drew's Roll.
- TNA:WO 25/3901, Records of Service - Officers of the Medical Department (1790–1847).
- Succession Book Vol 12. Returns of service of medical officers in the Regular Army.
- Naval and Military Medical Services Br Med J (1886), 1:1198 (Published 19 June 1886).