| Name (1649 results) | Rank | Regiment |
|---|---|---|
| Orr, Robert Clifford | Captain | Somerset Light Infantry |
| O'Sullivan, Donald | ||
| O'Sullivan, Arthur Moore | Captain | 1st Royal Irish Rifles |
| O'Sullivan, Gerald Robert | Captain | 1st Royal Inniskilling Fusiliers |
| O'Sullivan, John Anthony | Second Lieutenant | Royal Flying Corps |
| O'Sullivan, J.J. | Captain | Royal Army Medical Corps |
| Otway, Herbert Francis | Lieutenant | Prince of Wales 's Leinster Regiment (Royal Canadians) |
| Oulton, William Plato | Lieutenant | 3rd Batt. Royal Dublin Fusiliers |
| Oulton, Harry Charles | Second Lieutenant | Leinster Regiment |
| Ozanne, Edward Graeme | Captain | 7th Royal Fusiliers (City of London Regiment) |