| Regimental number | 7/1501 |
| Date of birth | |
| Place of birth | Timaru |
| Religion | Roman Catholic |
| Occupation | Horse trainer |
| Address | 162 Salisbury Street, Christchurch |
| Marital status | Single |
| Age at embarkation | 32.2 |
| Height | 5' 5.5" |
| Weight | 164 lbs |
| Next of kin | Mother, Mrs E O'Brien, 162 Salisbury Street, Christchurch |
| Previous military service | Nil |
| Enlistment date | |
| Place of enlistment | Trentham |
| Rank on embarkation | Trooper |
| Enlistment status | Volunteer |
| Unit name | New Zealand Expeditionary Force, 6th Reinforcements, Canterbury Mounted Rifles |
| Embarkation details | Unit embarked from Wellington on board Tofua on |
| Final rank | Trooper |
| Final unit | Canterbury Mounted Rifles Regiment |
| Fate | Died of disease |
| Age at death from cemetery records | 38 |
| Place of burial | Ismailia War Memorial Cemetery (Row C, Grave No 20), Egypt |
| Family/military connections | Brother: 3547 Pte Thomas O'BRIEN, 10th Light Horse Regiment, AIF, returned to Australia, 10 July 1919. |
| Other details |
War service: Egypt, Gallipoli, Palestine Died of broncho pneumonia, 2nd Australian Stationary Hospital, Moascar, 10 March 1919. Medals: 1914-15 Star, British War Medal, Victory Medal |
| Miscellaneous details | Nominal Roll Vol. 1: Canterbury Mounted Rifles/Sixth |
| Sources | Archives New Zealand (Wellington), Agency AABK, Series 18805, File 21381357 |