World War II

O’Brien earned six bronze service star during World War II: one on her European-African-Middle Eastern Campaign Ribbon and five on her Asiatic-Pacific Campaign Ribbon as follows:
1 Star INVASION OF NORMANDY
6–25 June 1944.
1 Star LEYTE OPERATION
Luzon attack: 13–19 November 1944.
Ormoc Bay landings: 7–8 December 1944.
1 Star LUZON OPERATION
Mindoro landings, 12–18 December 1944.
1 Star IWO JIMA OPERATION
Fifth Fleet raids against Honshu and Nansei Shoto: 4 January–1 March 1945.
Assault and occupation of Iwo Jima: 15 February–1 March 1945.
1 Star OKINAWA OPERATION
Assault and occupation of Okinawa: 25 March–1 April 1945.
1 Star CONSOLIDATION OF SOUTHERN PHILIPPINES
Mindoro Island landings 20 July 1945.

Korean War

O’Brien earned five bronze service stars on her Korean Service Ribbon as follows:
1 Star FIRST U.S. COUNTER OFFENSIVE 1951
9 March–7 April 19512.
1 Star COMMUNIST CHINA SPRING OFFENSIVE 1951
13 May–27 June 1951.
1 Star U.N. SUMMER-FALL OFFENSIVE 1951
11 July–21 September 1951.
1 Star KOREAN DEFENSE, SUMMER-FALL 1952
23 July–25 October 1952.
1 Star THIRD KOREAN WINTER, 1952–53
10–22 December 1952.