 The German plan of attack was influenced by their army 's experiences during the Battle of France . Their strategy was to create a diversion through the campaign in Albania , thus stripping the Hellenic Army of manpower for the defence of their Yugoslavian and Bulgarian borders . By driving armoured wedges through the weakest links of the defence chain , penetrating Allied territory would not require substantial armour behind an infantry advance . Once Southern Yugoslavia was overrun by German armour , the Metaxas Line could be outflanked by highly mobile forces thrusting southward from Yugoslavia . Thus , possession of Monastir and the Axios valley leading to Thessaloniki became essential for such an outflanking maneuver . 
