| Regimental number | 4088 |
| Place of birth | Goondiwindi, Queensland |
| Religion | Roman Catholic |
| Occupation | Stock Inspector |
| Address | NSW Stock Office, Goondiwindi, Queensland |
| Marital status | Single |
| Age at embarkation | 25.7 |
| Height | 5' 9.5" |
| Weight | 182 lbs |
| Next of kin | Mother, Mrs Margaret Brennan, Goondiwindi, Queensland |
| Previous military service | Nil |
| Enlistment date | |
| Date of enlistment from Nominal Roll | |
| Place of enlistment | Toowoomba, Queensland |
| Rank on enlistment | Private |
| Unit name | 26th Battalion, 10th Reinforcement |
| AWM Embarkation Roll number | 23/43/3 |
| Embarkation details | Unit embarked from Brisbane, Queensland, on board HMAT A73 Commonwealth on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 26th Battalion |
| Fate | Returned to Australia |
| Discharge date | |
| Family/military connections | Brothers: 57772 Corporal Malcolm Maurice BRENNAN, Signals Engineers Details, returned to Australia, 15 November 1919; 1854 Driver William Vincent BRENNAN, 2nd Field Artillery Brigade, returned to Australia, 27 August 1917. |
| Other details |
War service: Western Front Commenced return to Australia on board HT 'Ypiringa', 12 November 1919; discharged (termination of period of enlistment), Brisbane, 24 March 1920. Medals: British War Medal, Victory Medal |
| Date of death | |
| Age at death | 69 |
| Place of burial | Goondiwindi Cemetery, Queensland |
| Sources | NAA: B2455, BRENNAN Clarence Francis |