| O'Bryen | J G P | | Trooper | Natal 1906 (1)
Source: Recipients of the Natal 1906 Medal | Royston's Horse |
| O'Byrne | A | | | 3rd Battalion
Source: QSA and KSA medal rolls | (King's) Liverpool Regiment |
| O'Byrne | L | | | 2nd Battalion
Source: QSA and KSA medal rolls | Royal Dublin Fusiliers |
| O'Byrne | Michael | 40784 | Private | Source: QSA Medal Rolls | 131st Company, 29th Btn, IY |
| O'Byrne | W | 3149 | Private | QSA (2). Invalided to England.
Source: QSA medal rolls | 9th (The Queen's Royal) Lancers |
| O'Caill | L S | | | District 1
Source: QSA and KSA rolls | Cape Police |
| O'Callagan | H | | | Source: WO100/146 | No 10 Mountain Battery, RGA |
| O'Callagan | H | | | Source: QSA and KSA medal rolls | No 10 Mountain Battery, RGA |
| O'Callagan | J | 2331 | Conductor | Weil's Transport. Medal returned or issued elsewhere
Source: QSA and KSA medal rolls | Imperial Transport Service |
| O'Callaghan | C | | | 2nd Battalion
Source: Medal rolls | Royal Munster Fusiliers |
| O'Callaghan | C P | 7165 | Sapper | Later to 38th Field Company. QSA (3) issued 6 Aug 1904. Clasp SA01 issued 28 Feb 1906.
QSA (4) CC OFS SA01 SA02
TNA ref 158/22; 159/62; 159/90 | Royal Engineers, Telegraph Battalion |
| O'Callaghan | Charles | 441 | Trooper | Source: Nominal roll in WO127 | Kimberley Horse |
| O'Callaghan | Charles | 100 | Private | Source: OZ-Boer database | Queensland, 3rd Mounted Infantry Contingent |
| O'Callaghan | D | | | 3rd Battalion
Source: QSA and KSA medal rolls | Northamptonshire Regiment |
| O'Callaghan | D | | | 1st Battalion
Source: Medal rolls | Royal Munster Fusiliers |
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