Liberal Party politician Eleftherios Venizelos. With Allied assistance, they launched a coup which secured Thessaloniki and most of Greek Macedonia, causing the National Schism. In June 1917, the Venizelists gained full control of the country, immediately declaring war on the Central Powers and joining the Allied Army of the Orient operating on the Balkan Front. The Greek entry into the war along with the 24 division reinforcements that the Army had received in the spring of the same year had created a strategic advantage for the Entente. On 30 May 1918, the Allies launched an offensive on the heavily fortified Skra salient, commencing the battle of Skra-di-Legen. Utilizing the cover of heavy artillery a Franco-Hellenic force made a rapid push into the enemy trenches, conquering Skra and the surrounding system of fortifications. Greek casualties amounted to 434–440 killed in action, 154–164 missing in action and 1,974–2,220 wounded, France lost approximately 150 men killed or injured. A total of 1,782 soldiers of the Central Powers became prisoners of war, including a small number of German engineers and artillery specialists that served in Bulgarian units; considerable amounts of military equipment also fell into Entente hands. The plan for a Bulgarian counterattack against Skra remained unfulfilled as the Bulgarian soldiers refused to take part in the operation. Both the Greek and the French press used the opportunity to extol the efforts of the Greek army, favorably influencing the Greek mobilization. The fall of Skra prompted Bulgarian prime minister Vasil Radoslavov to resign on 21 June 1918. Aleksandar Malinov who assumed office immediately afterwards pursued secret negotiations with Britain, offering Bulgaria's exit from the war with the condition that Bulgaria fully retain eastern Macedonia. However, British prime minister David Lloyd George rejected the proposal, assuring the Greek ambassador in London Ioannis Gennadius, that Britain would not act against Greek interests. In late July 1918, Bulgarian commander-in-chief Nikola Zhekov sent German Field Marshal Paul von Hindenburg a message regarding a rumored Entente offensive, and detailed Bulgaria's inability to adequately defend the Vardar portion of the front. Zhekov requested that Germany immediately reinforce the Balkan Front, hinting that Austria-Hungary would also be required to strengthen its positions in Albania. On 17 August, Hindenburg pledged to provide Bulgaria with support once the situation on other front permits it. Hindenburg's reluctance to support Bulgaria was also manifested by the early September redeployment of the last German Jäger battalion