| Regimental number | 3511 |
| Place of birth | Tunnack Tasmania |
| Religion | Baptist |
| Occupation | Reader |
| Address | Hobart, Tasmania |
| Marital status | Single |
| Age at embarkation | 18 |
| Next of kin | Father, Thomas Lucas O'Brien, Tunnack, Tasmania |
| Enlistment date | 16 May 1917 |
| Date of enlistment from Nominal Roll | 26 March 1917 |
| Rank on enlistment | Private |
| Unit name | 3rd Light Horse Regiment, 30th Reinforcement |
| AWM Embarkation Roll number | 10/8/5 |
| Embarkation details | Unit embarked from Melbourne, Victoria, on board HMAT A73 Commonwealth on 2 November 1917 |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 3rd Light Horse Regiment |
| Fate | Returned to Australia 15 May 1919 |
