A native of Galway city, Maj-Gen Maureen O’Brien graduated from University College Galway (UCG) with B.Sc. and H.Dip. Ed before being awarded a cadetship in Óglaigh na hÉireann in 1981. On her commissioning in 1983, she was posted as an infantry officer to the 4th Infantry Battalion in Cork, returning to the Cadet School some years later as an instructor.
Since then Major Gen O’Brien has held many different appointments in operations, training and strategic planning. At home she has served in Cork, Defence Forces HQ, Eastern Brigade HQ (Cathal Brugha Barracks, Rathmines), Aiken Bks in Dundalk and the Military College.
In 2011 she became the first woman to be promoted to the rank of Lieutenant Colonel and in 2012 became the first woman to command an infantry battalion when she was appointed Officer Commanding 27th Infantry Battalion in Dundalk. For the next two years, she served in the Operations Branch of Defence Forces Headquarters in which she was the senior staff officer responsible for EU and NATO/PfP engagement.
Prior to her promotion to Brigadier General, she was Director of Communications and Information Services.
During her career, Maj-Gen O’Brien has amassed extensive overseas service. Her first two deployments were to Lebanon (UNIFIL). She has also served in Western Sahara (MINURSO) and East Timor (UNTAET). She was seconded to the Organisation for Security and Cooperation in Europe (OSCE) in Sarajevo (BiH) for eighteen months. In 2009 she became the first woman to serve as the Deputy Commanding Officer of an infantry battalion when deployed to Chad (MINURCAT). She also served as Chief of Operations Planning, Sector HQ in Lebanon. She recently concluded her tour as Deputy Force Commander UNDOF where she was deployed to Syria for 18 months, returning in March 2021. She spent many months acting as Force Commander.
Maj Gen O’Brien completed a Post Graduate Diploma in IT from UCC and holds a first-class Masters Degree in Leadership, Management and Defence Studies (NUIM).