 At dawn on 6 April , the German armies invaded Greece , while the Luftwaffe began an intensive bombardment of Belgrade . The XL Panzer Corps — planned to attack across southern Yugoslavia — began their assault at 05 : 30 . They pushed across the Bulgarian frontier at two separate points . By the evening of 8 April , the 73rd Infantry Division captured Prilep , severing an important rail line between Belgrade and Thessaloniki and isolating Yugoslavia from its allies . On the evening of 9 April , Stumme deployed his forces north of Monastir , in preparation for attack toward Florina . This position threatened to encircle the Greeks in Albania and W Force in the area of Florina , Edessa and Katerini . While weak security detachments covered his rear against a surprise attack from central Yugoslavia , elements of the 9th Panzer Division drove westward to link up with the Italians at the Albanian border . 
