The Allies now began to bring pressure to bear on the Greek Government in order that the Greek Army should be withdrawn from Macedonia and demobilized. On January 28th an Anglo-French detachment, with the co-operation of warships, among which was the Italian cruiser _Piemonte_, occupied the forts of Karaburun, south-east of Salonica, the port of which is dominated by them, and expelled the Greek garrison. On the night of January 31st-February 1st, a German Zeppelin bombarded Salonica; it was afterwards brought down and destroyed near the mouth of the Vardar, and at the same time luminous signals were seen coming from the city. General Sarrail, who since January 15th had assumed the control of the police, the railways and the telegraph, seized the occasion to proclaim the state of siege. The chief of the French _Sûreté_ and the British A.P.M. proceeded little by little to cleanse the town of suspicious elements, and there was good need of it. In the meanwhile the Greek troops slowly and unwillingly began to evacuate Macedonia. On May 23rd, 1916, the Germano-Bulgar Army, on the pretext that the Allies were carrying out threatening movements in the Serres area, crossed the Greek frontier and demanded the evacuation of Fort Rupel dominating the narrow defile through which the Struma opens its way to the east Macedonian plain and flows down to the sea. The Commander of the garrison made a feeble protest, fired a few shots to salve his conscience, and asked for instructions from Athens. These were to the effect that he should hand over the fort with all its material, which he did with enthusiasm. In conformity with analogous instructions, the whole of the IV Corps, distributed through the Serres area and commanded by Colonel Hadzopoulos, surrendered to the Bulgarians and Germans, except 2,500 men of the Serres Division who, with their Commander, Colonel Christodoulos, refused to submit to this dishonour and managed to escape to the island of Thasos, whence in September they were transported to Salonica and formed the nucleus of the future Venizelist army.