| Regimental number | 1602 |
| Place of birth | Ennis, Co Clare, Ireland |
| Religion | Roman Catholic |
| Occupation | Labourer |
| Marital status | Single |
| Age at embarkation | 28 |
| Height | 5' 9" |
| Weight | 160 lbs |
| Next of kin | Mrs M A McMahon, Kilmaley, Ennis, County Clare, Ireland |
| Previous military service | Served for 8 years in the Dublin Fusiliers (time expired). |
| Enlistment date | |
| Place of enlistment | Liverpool, New South Wales |
| Rank on enlistment | Private |
| Unit name | 2nd Battalion, 3rd Reinforcement |
| AWM Embarkation Roll number | 23/19/2 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT A49 Seang Choon on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 2nd Battalion |
| Fate | Killed in Action |
| Date of death | |
| Age at death from cemetery records | 29 |
| Place of burial | Lone Pine Cemetery (Plot II, Row C, Grave No. 6), Gallipoli, Turkey |
| Panel number, Roll of Honour, Australian War Memorial | 33 |
| Miscellaneous information from cemetery records | Parents: John and Mary MCMAHON, Kilmaley, Ennis, Co. Clare, Ireland |
| Other details |
War service: Egypt, Gallipoli Joined 2nd Bn at Gallipoli, 7 May 1915. Killed in action, 20 May 1915. Graves Registration Unit, Alexandria, noted, 17 July 1917: 'No trace gravesite'. Medals: 1914-15 Star, British War Medal, Victory Medal |
| Sources | NAA: B2455, McMAHON Thomas |