| Regimental number | 354 |
| Place of birth | Wandong, Victoria |
| School | James Street State School, Perth, Western Australia |
| Religion | Church of England |
| Occupation | Butcher |
| Address | Tenth Avenue, Maylands, Western Australia |
| Marital status | Single |
| Age at embarkation | 20 |
| Height | 5' 6.25" |
| Weight | 142 lbs |
| Next of kin | Carl Siefken, Tenth Avenue, Maylands, Western Australia |
| Previous military service | Served for 3 years as a Bugler in the 11th Western Australian Infantry Regiment, Citizen Military Forces. |
| Enlistment date | |
| Date of enlistment from Nominal Roll | |
| Place of enlistment | Blackboy Hill, Western Australia |
| Rank on enlistment | Bugler |
| Unit name | 11th Battalion, C Company |
| AWM Embarkation Roll number | 23/28/1 |
| Embarkation details | Unit embarked from Fremantle, Western Australia, on board HMAT A11 Ascanius on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 3rd Machine Gun Company |
| Fate | Died whilst a Prisoner of War |
| Place of death or wounding | Gerdauen, Germany |
| Age at death | 23 |
| Age at death from cemetery records | 23 |
| Place of burial | Berlin South-Western Cemetery (Plot XV, Row B, Grave No. 10), Stahnsdorf, Germany |
| Panel number, Roll of Honour, Australian War Memorial | 176 |
| Miscellaneous information from cemetery records | Parents: Carl and Caroline SIEFKEN. Native of Wandong, Victoria |
| Family/military connections | Brother: 4899 Pte Carl William SIEFKEN, 51st Bn, returned to Australia, 28 February 1919. |
| Other details |
War service: Egypt, Gallipoli, Western Front Embarked, 3 October 1914; disembarked Egypt, 8 December 1914. Embarked to join the Mediterranean Expeditionary Force (Gallipoli Campaign), 2 March 1915. Evacuated to hospital, 16 August 1915; admitted to HS 'Ascania', Mudros, 19 August 1915; disembarked Malta, 25 August 1915, and transferred to St David's Military Hospital the same day; to England, 5 September 1915; to hospital, Fulham, 14 September 1915 (influenza, and diarrhoea). Found guilty, 3rd Training Bn, Perham Downs, 18 July 1916, of being absent from 1400 hours parade: awarded 3 days' confined to camp. Proceeded overseas to France, 25 July 1916; marched into 1st Australian Divisional Base Depot, Etaples, 26 July 1916. Proceeded to unit, 8 August 1916; rejoined 11th Bn, 9 August 1917. Transferred to, and taken on strength of 3rd Machine Gun Company, 11 February 1917. Posted as 'Missing in Action', 15 April 1917. Now, 6 July 1917, reported as 'Prisoner of War, 15 April 1917, and interned Limburg, Germany'. Died, Gerdauen, East Prussia, 21 October 1918 (pneumonia and influenza). Medals: 1914-15 Star, British War Medal, Victory Medal |
| Miscellaneous details | Surname entered incorrectly on Embarkation Roll as SIEFKIN. |
| Sources | NAA: B2455, SIEFKEN Otto John |