Corporal 3395 Matthew Kennedy O'BRIEN - King's (Liverpool Regiment), 1st/10th Bn.
Quartermaster Serjeant 3451 James Henry O'BYRNE - Manchester Regiment, 13th Bn.
Private 35877 Thomas O'CONNELL - Cameronians (Scottish Rifles), 7th Bn.
Private 25203 John O'DONNELL - Royal Inniskilling Fusiliers, 8th Bn.
Private 306772 Edward O'NEALE - King's (Liverpool Regiment), 8th Bn.
Thomas O'NEIL - , Unidentified
Sapper 6901 William Thomas O'NEIL - Royal Engineers, 2nd/1st West Lancs Field Coy.
Private 26592 John O'NEILL - King's (Liverpool Regiment), 17th Bn.
Private 25735 John O'NEILL - Machine Gun Corps, 3rd Bn.
Rifleman 2998 Joseph O'NEILL - South Lancashire Regiment, 1st/5th Bn.
Private 240478 Daniel O'REARDON - Loyal North Lancashire Regiment, 1st/5th Bn.
Harold O'REILLY - , Unidentified
Private 20047 Henry O'REILLY - South Lancashire Regiment, 11th Bn.
Private 6/348 Patrick O'SHAUGHNESSY - Royal Munster Fusiliers, 1st Bn.
Private 21054 William A OAKES - South Lancashire Regiment, 11th Bn.
Private 33036 Joseph Henry OLDFIELD - Welsh Regiment, 8th Bn.
Private 17144 William ORFORD - South Lancashire Regiment, 8th Bn. 'C' Coy.
Pioneer WR/314516 Thomas ORMOND - Royal Engineers, Inland Water Transport
Lance Corporal 241127 James Richard ORMROD - South Lancashire Regiment, 2nd/5th Bn.
Private TR3/14845 Matthew ORMROD - Training Reserve., 49th
Private 23111 Charles ORR - King's Own (Royal Lancaster Regiment), 3rd Bn.
Private 52875 Harold ORRELL - Durham Light Infantry, 1st/5th Bn.
Private 35847 Peter ORRELL - King's (Shropshire Light Infantry), 1st/4th Bn.
Private 202886 James OUSALICE - Lancashire Fusiliers, 1st/5th Bn.
Private 21316 Francis OVENS - South Lancashire Regiment, 11th Bn.
Air Mechanic 3rd Class 101904 Peter OVENS - Royal Air Force,
Corporal 1586 Ernest OWEN - South Lancashire Regiment, 1st/5th Bn.
Private 21682 George OWEN - South Lancashire Regiment, 11th Bn.
Private 27289 Herbert OWEN - South Lancashire Regiment, 2nd Bn.
Serjeant 1012 Joseph OWEN - South Lancashire Regiment, 1st/5th Bn.
Private 11694 Robert OWEN - King's (Liverpool Regiment), 1st Bn.
Private 5278 Thomas OWEN - Lancashire Fusiliers, 9th Bn.
Private 1234 Thomas OWEN - Royal Fusiliers, 8th Bn.
Private 83911 Thomas Hammond OWEN - Machine Gun Corps, 51st Bn.
Gunner 199396 Wilfred OWEN - Royal Garrison Artillery,
Private 14488 William OWEN - Machine Gun Corps, 76th Coy.
Rifleman 242238 Charles OWENS - South Lancashire Regiment, 2nd/5th Bn.
Company Serjeant Major 15804 John OWENS - King's Own (Royal Lancaster Regiment), 8th Bn.
Civilian Owen Hugh OWENS - Civilian, SS Arabic
Private 11692 Thomas OWENS - King's (Liverpool Regiment), 1st Bn.