| Date of birth | |
| Religion | Roman Catholic |
| Occupation | Banana planter |
| Address | Highlands Figtree Pocket, Indooroopilly, Brisbane, Queensland |
| Marital status | Single |
| Age at embarkation | 38 |
| Next of kin | Father, James O'Brien, Highlands, Figtree Pocket, Indooroopilly, Brisbane, Queensland |
| Enlistment date | |
| Rank on enlistment | Captain |
| Unit name | 41st Battalion, C Company |
| AWM Embarkation Roll number | 23/58/1 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT A64 Demosthenes on |
| Rank from Nominal Roll | Captain |
| Unit from Nominal Roll | 41st Battalion |
| Promotions |
Captain Unit: 41st Battalion Promotion date: |
| Fate | Effective abroad (still overseas) |