|Address||38 Bulamana Road, Ultimo, Sydney, New South Wales|
|Age at embarkation||38|
|Next of kin||Wife, Mrs M O'Brien, 448 Jones Street, Ultimo, Sydney, New South Wales|
|Rank on enlistment||Private|
|Unit name||Light Trench Mortar Battery, Reinforcement 4|
|AWM Embarkation Roll number||13/130/2|
|Embarkation details||Unit embarked from Sydney, New South Wales, on board HMAT A24 Benalla on
|Rank from Nominal Roll||Private|
|Unit from Nominal Roll||1st Battalion|
|Recommendations (Medals and Awards)||
'Work near Hargicourt 18-21 September 1918'.
|Fate||Returned to Australia
'In the operations near HARGICOURT from 18th to 21st September, 1918, Private O'BRIEN showed great courage and devotion to duty. On 18th September, 1918, as a Lewis Gunner he performed most valuable work getting well forward with his gun and providing covering fire for the remainder of the platoon, while enemy points of resistance were being attacked, during period of exploitation after barrage has ceased. On 21st September, 1918, he again performed most valuable work with his gun, inflicting many casualties on the enemy who could be seen moving about after the objective had been captured and showed good choice of position for his gun. Throughout he set a fine example of courage and initiative, and greatly assisted in the taking and consolidation of the objectives assigned to his platoon.'
Source: 'Commonwealth Gazette' No. 115
War service: Western FrontMedals: Military Medal, British War Medal, Victory Medal