Heeresgruppe F
Developments in Romania in late August 1944 confronted Army Group F command with the necessity of an immediate large-scale concentration of troops and weapons in Serbia in order to cope with a threat from the east. The Allied command, and the NOVJ supreme command, predicted this scenario and developed a plan for the occasion. On 1 September 1944, a general attack from the ground and from the air on the German transport lines and installations (Operation Ratweek) began. These attacks largely hindered German troop movements, with units disassembled and tied to the ground.