Mackensen) which operated in Poland between 22 April 1915 and 8 September 1915 during World War I under the command of Field Marshal August von Mackensen, was an army group of the Imperial German Army.
In June 1916, the Army Group faced the Brusilov Offensive.
After an initial retreat, it checked the Russian advance at the Battle of Kowel.
After the signing of the Treaty of Brest-Litovsk in March 1918, the Army Group occupied Ukraine.
On 31 March 1918, von Linsingen was replaced by Hermann von Eichhorn and the Army Group was renamed Army Group Eichhorn-Kiev (German: Heeresgruppe Eichhorn-Kiew).