| Regimental number | 2866 |
| Religion | Roman Catholic |
| Occupation | Grazier |
| Address | Tallwood Station, Walgett, New South Wales |
| Marital status | Single |
| Age at embarkation | 20 |
| Next of kin | Father, James Thomas O'Brien, Tallwood Station, Walgett, New South Wales |
| Enlistment date | |
| Rank on enlistment | Private |
| Unit name | 3rd Pioneer Battalion, Reinforcement 5 |
| AWM Embarkation Roll number | 14/15/2 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT A24 Benalla on |
| Regimental number from Nominal Roll | 2866A |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 35th Battalion |
| Fate | Returned to Australia |
| Other details |
War service: Western Front Medals: British War Medal, Victory Medal |