| Regimental number | 2477 |
| Place of birth | Doctor's Hill, King Williamstown, Cork County, Ireland |
| School | King Williamstown School, Ireland |
| Other training | Nil |
| Age on arrival in Australia | 23 |
| Religion | Roman Catholic |
| Occupation | Labourer |
| Address | Charleville, Queensland |
| Marital status | Single |
| Age at embarkation | 29 |
| Next of kin | Father, Thomas O'Callaghan, Charleville, Queensland |
| Previous military service | Nil |
| Enlistment date | |
| Rank on enlistment | Private |
| Unit name | 2nd Light Horse Regiment, 17th Reinforcement |
| AWM Embarkation Roll number | 10/7/4 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT A10 Karroo on |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 2nd Light Horse Regiment |
| Other details from Roll of Honour Circular | 'Had a hard life, sent out to "service" to earn more, to help support a very big dad, at the early age of 10 and 11 years.' (Information supplied by mother). |
| Fate | Killed in Action |
| Place of death or wounding | Romani |
| Age at death | 33 |
| Place of burial | Kantara War Memorial Cemetery (Row B, Grave No. 41), Egypt |
| Panel number, Roll of Honour, Australian War Memorial | 3 |
| Miscellaneous information from cemetery records | Parents: Ellen and the late Cornelius O'CALLAGHAN, Doctor's Hill, KINGWILLIAMSTOWN, Co. Cork, Ireland |
| Family/military connections | Brother: 474 Pte Michael O'CALLAGHAN, 15th Bn, killed in action, 8 August 1915. |
| Other details |
War service: Egypt Medals: British War Medal, Victory Medal |
| Miscellaneous details | Note difference in details re father: Embarkation Roll states father to be Thomas O'CALLAGHAN; OWG File gives father as the late Cornelius O'CALLAGHAN. |