the command of Major Georgios Douratsos of the 14th Division defended Fort Roupel. The Germans had to break the Metaxas line, in order to capture Thessaloniki, Greece's second-largest city and a strategically important port. The attack started on 6 April with one infantry unit and two divisions of the XVIII Mountain Corps. Due to strong resistance, the first day of the attack yielded little progress in breaking the line. A German report at the end of the first day described how the German 5th Mountain Division "was repulsed in the Rupel Pass despite strongest air support and sustained considerable casualties". Two German battalions managed to get within of Fort Rupel on 6 April, but were practically destroyed. Of the 24 forts that made up the Metaxas Line, only two had fallen and only after they had been destroyed. In the following days, the Germans pummelled the forts with artillery and dive bombers and reinforced the 125th Infantry Regiment. Finally, a high snow-covered mountainous passage considered inaccessible by the Greeks was crossed by the 6th Mountain Division, which reached the rail line to Thessaloniki on the evening of 7 April. The 5th Mountain Division, together with the reinforced 125th Infantry Regiment, crossed the Struma river under great hardship, attacking along both banks and clearing bunkers until they reached their objective on 7 April. Heavy casualties caused them to temporarily withdraw. The 72nd Infantry Division advanced from Nevrokop across the mountains. Its advance was delayed by a shortage of pack animals, medium artillery and mountain equipment. Only on the evening of 9 April did it reach the area north-east of Serres. Most fortresses—like Fort Roupel, Echinos, Arpalouki, Paliouriones, Perithori, Karadag, Lisse and Istibey—held until the Germans occupied Thessaloniki on 9 April, at which point they surrendered under General Bakopoulos' orders. Nevertheless, minor isolated fortresses continued to fight for a few days more and were not taken until heavy artillery was used against them. This gave time for some retreating troops to evacuate by sea. Although eventually broken, the defenders of the Metaxas Line succeeded in delaying the German advance. Capitulation of the Greek army in Macedonia The XXX Infantry Corps on the left wing reached its designated objective on the evening of 8 April, when the 164th Infantry Division captured Xanthi. The 50th Infantry Division advanced far beyond Komotini towards the Nestos river. Both divisions arrived the next day. On 9 April,