Lewis, Jon The Forgotten Front. The Macedonian Campaign 1915-1918

The Macedonian Campaign has been largely ignored by history. Such neglect is misplaced. The annals of the First World War hold few events to compare with the triumphant final offensive of the Allied Army of the East, and the whole story of the campaign is rich, diverse and relevant.
Almost accidental in its origins the reality of a six-nation Allied army gradually took shape. The terrain fought over, from marshy river valleys to 2000 metre mountain ranges, presented special military challenges. The ambivalent position of Greece, the Romanian misadventure, the intricacy of Balkan politics, the depredations of malaria, and inter-allied tensions both in Macedonia and at Allied government level all added further layers of complexity. But in the end the Allied Army of the East met its defensive objectives and vastly exceeded its offensive ones.
The campaign had its origins in October 1915 when a small FrancoBritish force disembarked at Salonica, with orders to advance into Serbia to aid the beleaguered Serbs. It was too late, but a large part of the Serbian Army escaped to the Adriatic. Reconstituted into six divisions it was subsequently shipped to Salonica to form part of an Allied force of 15 divisions under the command of General Maurice Sarrail. By the end of 1916 the Allied Army of the East, with contingents also from Italy and Russia, had expanded into 20 divisions.
Apart from tying down a substantial GermanoBulgarian army, the Allied armys objectives were to prevent the Central Powers from breaking into Greece, to bring Greece and its army into the Allied camp, and, above all, to prepare for actions and advances into Bulgaria and enemy-held Serbia from the south.
While the first two of these objectives were met, territorial gains in 1916 and 1917 were limited. The Serbians consolidated a strong position to the west of the Moglena mountain range, and with the French advanced into Serbia as far as Monastir. The British fought successful actions in the Struma valley but suffered costly reverses against the virtually impregnable Bulgarian defences west of Lake Doiran on two occasions.
Then in 1918 a key leadership change was made with the appointment of General Franchet dEspèrey. In September under his dynamic command French and Serbian forces finally punched their way through the Bulgarian lines in the centre of the Moglena mountains, and, supported by a Franco-Italian force on their left and a British-Greek force on their right, advanced at a phenomenal pace towards the upper Vardar and Skopje, splitting the enemy forces into two. Within 15 days the Bulgarians capitulated. This was followed shortly and inevitably by an armistice with Turkey.

While the First World War was won and lost on the Western Front, the defeat of Bulgaria in September 1918 and the relentless advance of the Allied Army towards the undefended Danube frontier played a critical role, recognised also by the German High Command, in bringing the war to a close before the end of the year.