History: by Jason Pipes and Ron Klages @ Feldgrau.com
The 12. Armee was established on 13 October 1939. Initially they served as security on the Western Frontier in the Eifel from 13 October 1939 through 9 May 1940. Beginning on 10 May 1940 through 25 June 1940 they fought in the Western Campaign and then from 26 June 1940 through the end of December 1940 they served as occupying forces in France.
From 3 January 1941 through 5 April 1941 they were located first in Rumania then in Bulgaria.
From 6 April 1941 through 10 May 1941 they fought in the Balkan Campaign, first in Yugoslavia and then in Greece. From 11 May 1941 until 23 January 1943 they serve as occupation forces in Greece, Crete and the Aegean Islands. They were dissolved on 23 January 1943 becoming Heeresgruppe āEā. They were in the Balkans from 3 January 1941 through 23 January 1943, a total of 751 days.
The 12. Armee was reformed on 10 April 1945 from remnants of Heeresgruppenkommandos Nord. They fought to the end in the east.