| Regimental number | 4829 |
| Place of birth | Marion, South Australia |
| Religion | Roman Catholic |
| Occupation | Brick maker |
| Address | Marion Post Office, Marion, South Australia |
| Marital status | Single |
| Age at embarkation | 22 |
| Next of kin | Mother, Mrs J McMahon, Jacob Street, Marion, South Australia |
| Enlistment date | |
| Rank on enlistment | Private |
| Unit name | 10th Battalion, 15th Reinforcement |
| AWM Embarkation Roll number | 23/27/4 |
| Embarkation details | Unit embarked from Adelaide, South Australia, on board RMS Mongolia on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 10th Battalion |
| Fate | Returned to Australia |
| Miscellaneous information from cemetery records | Parents: Michael and Julie MCMAHON |
| Family/military connections | Brother: 567 Pte Nicholas McMAHON, Army Provost Corps, returned to Australia, 3 December 1918. |
| Other details |
War service: Western Front Medals: British War Medal, Victory Medal |
| Date of death | |
| Age at death | 35 |
| Place of burial | St Jude's Church of England Cemetery, Brighton, South Australia |