| Regimental number | 2210 |
| Religion | Roman Catholic |
| Occupation | Labourer |
| Address | 395 Moorabool Street, South Geelong, Victoria |
| Marital status | Single |
| Age at embarkation | 20 |
| Next of kin | Father, M. O'Callaghan, 395 Moorabool Street, South Geelong, Victoria |
| Enlistment date | 6 January 1915 |
| Rank on enlistment | Private |
| Unit name | 5th Battalion, 6th Reinforcement |
| AWM Embarkation Roll number | 23/22/2 |
| Embarkation details | Unit embarked from Sydney, New South Wales, on board HMAT A40 Ceramic on 25 June 1915 |
| Rank from Nominal Roll | Private |
| Unit from Nominal Roll | 46th Battalion |
| Fate | Returned to Australia 16 October 1916 |
| Miscellaneous details (Nominal Roll) | *Spelt William Brian O'Callaghan on NR |
