 By the morning of 10 April , the XL Panzer Corps had finished its preparations for the continuation of the offensive and advanced in the direction of Kozani . The 5th Panzer Division , advancing from Skopje encountered a Greek division tasked with defending Monastir Gap , rapidly defeating the defenders . First contact with Allied troops was made north of Vevi at 11 : 00 on 10 April . German SS troops seized Vevi on 11 April , but were stopped at the Klidi Pass just south of town , where a mixed Empire @-@ Greek formation — known as Mackay Force — was assembled to , as Wilson put it , " ... stop a blitzkrieg down the Florina valley . " During the next day , the SS regiment reconnoitered the Allied positions and at dusk launched a frontal attack against the pass . Following heavy fighting , the Germans broke through the defence . On 13 April , 70 supporting German bombers attacked Volos , the port almost being completely destroyed . By the morning of 14 April , the spearheads of the 9th Panzer Division reached Kozani . 
