| Regimental number | 5621 |
| Place of birth | Petersham New South Wales |
| Religion | Roman Catholic |
| Address | Walker Street, Casino, New South Wales |
| Marital status | Single |
| Age at embarkation | 25 |
| Next of kin | Father, William Edward O'Brien, Walker Street, Casino, New South Wales |
| Enlistment date | 17 May 1915 |
| Rank on enlistment | Private |
| Unit name | Infantry Brigade 4, Field Ambulance 5, Reinforcement 5 |
| AWM Embarkation Roll number | 26/48/2 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT A4 Pera on 12 October 1915 |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 5th Field Ambulance |
| Fate | Returned to Australia 19 August 1919 |
