| Regimental number | 2574 |
| Place of birth | Karridale, Western Australia |
| Religion | Roman Catholic |
| Occupation | Labourer |
| Address | Hoffman Mill, Western Australia |
| Marital status | Single |
| Age at embarkation | 21 |
| Next of kin | Father, G Brennan, Hoffman Mill, Western Australia |
| Enlistment date | 8 May 1915 |
| Date of enlistment from Nominal Roll | 3 May 1915 |
| Rank on enlistment | Private |
| Unit name | 11th Battalion, 8th Reinforcement |
| AWM Embarkation Roll number | 23/28/2 |
| Embarkation details | Unit embarked from Fremantle, Western Australia, on board HMAT A68 Anchises on 2 September 1915 |
| Rank from Nominal Roll | Lance Corporal |
| Unit from Nominal Roll | 51st Battalion |
| Fate | Returned to Australia 1 May 1919 |
| Family/military connections | Brother: 2438 Pte John Augusta BRENNAN, 16th Bn, returned to Australia, 9 February 1919. |