Papapostolou Serafeim graduated from Hellenic Army Academy in 1975. He served in Armoured and Reconnaissance Units for more than 20 years. He became Commander of the 12th Armor Battalion (1993) and C’ Reconnaissance Battalion (1994-1995) in the borders area of Trace. For one year (1993-1994) he was deployed in North Iraq (Kurdistan), Commander (Suleimaniyah Sector) of UN Guards Contingent (UNGCI). He has served at the Hellenic Army HQs as Staff Officer responsible for the development of Main Battle Tanks fleet (1988-1992) and for Armaments Planning and Procurements (1997-1999). In August 1999, he moved to the Hellenic National Defence General Staff, where he became the senior officer for Operational Planning and Operations in Balkans. He served twice in the Former Yugoslavia, first (1992) as a military observer for a short period in Croatia, and second for one year, in KFOR Kossovo (2000-2001) as a Deputy Commander and Chief of Staff of 34th Mech Brigade (Hellenic Armed Forces in Kossovo). After his redeployment, he appointed in Hellenic National Defence General Staff as Director of National Crisis Management Center (2001-2003).
Additionally, he has served through staff assignments primarily in operations, plans, and crisis management. His assignments include three NATO tours: one as Military Assistant to Hellenic Military Representative at NATO HQs, Brussels (1995-1997), one with Joint Command South-cent (JCSC) at Larisa Greece (2003-2004), as J5 Branch Chief and his final staff assignment was as Assistance Chief of Staff (ACOS) Support of NATO’s Rapid Deployable Corps (NRDC-SP) Valencia, Spain (2004-2007). His last active duty assignment was Chief of Staff (COS) of C’ Corps/NATO’s Rapid Deployable Corps – Greece (NRDC-GR) (2007-2009).
He graduated successfully from all the basic and advanced Armor Schools, the Hellenic Army War College and the Hellenic National Defense College, as well as Oberammergau NATO School Specific Courses. In 1999, he attended Course 94 at the NATO Defense College.
He retired from the Hellenic Army on 13 February 2009, after more than 37 years of distinguished service.
General Papapostolou is a recognized leader and pioneer in conceptualizing, planning, and executing national security operations from humanitarian relief to major combat operations. For three years he was also President/CEO of ΔeltaCyrni Ltd Private Security Company (Maritime Security), consulting on global security matters and remains active in lecturing on military ops and the international security environment.