In First World War that started on August 1914 when after the assassination of Archduke Ferdinand in Sarajevo , Austria-Hungary declared war on Serbia. With the outbreak of the war Greece decided to remain neutral.

When rejecting the requirement of Bulgaria to grant the large southern part of Serbia , the port of Kavala and an area that included Serres , Bulgaria declared war against Serbia and the Anglo-French troops began to disembark in Thessaloniki / win. In Greek territories was a total of 80,000 army .

After Serbia had fallen into the hands of germanovoulgaron , they stopped at the Greek border and on 26 May 1916 a convoy germanovoulgaron proceeded in the direction Strymon Fortress Rupel .

At 9.45 commanding fortress commanded fire and halted the advance of the troops germanovoulgarikon . An order , however, by the then government, toppled the original plan, after stating that I had to become a tradition of Fortress and not be any resistance.

On 27 May 1916 , took delivery of Fortress Rupel which is one of the darkest pages of Greek history.

On August 5, 1916 , began the invasion all along the Greek-Bulgarian border. Portions of the 6th Division under the command of Colonel Christodoulou gave battle in Sidirokastrou without katarthosei stop the Bulgarian troops by 30 August had captured the town of Serres , Kavala and Drama.

The Fort of Rupel marked a challenge for the Germans in 1941 in their attempt to invade Greece . The resistance of the Greeks was admirable , since the German attack repulsed from the 6th to the morning of April 10 that stopped hostilities. The fort surrendered after the Germans invaded Greece.