World War One is known for the battle in Europe, and perhaps some of you have read about the failed campaign in Gallipoli. However the Allied Powers were also involved in Bulgaria and the Balkans. In 1915, Bulgaria declared war on the side of the Central Powers (Germany, Austria-Hungary), even though the Allied Powers tried to entice Bulgaria to side with them, the promises on land from Germany proved to sway their power to the Central Powers. This in turn would mean that they were at war against France, Russia and Great Britain, which leads us nicely to the invasion of the Balkans.
It must be noted however, that the actions taken by either side all link up. The landings at Gallipoli for example, bloody and worthless, brought a negative impact to the relations between Britain and Bulgaria. This is important as Bulgaria was seen as an important political and military ally, as Italy had only just entered the war on the side of the Entente, therefore the situation in the Balkans was extremely important. It therefore suggests that the role of Gallipoli was far worse than thought, as it was a political disaster, pushing Bulgaria towards the Central Powers.
Therefore on 6 September 1915, Bulgaria signed papers and made it known of their new-found friends which were the Central Powers. It led to the signing of three separate documents which would relate to the political and military situation that Bulgaria found itself in. The first of these documents were signed by the Prime minister and the German ambassador , it was to be called the Treaty of Amity and Alliance between the Kingdom of Bulgaria and the German Empire.
In the treaty it was agreed that both sides agreed not to enter an alliance or agreement directed against the other, which effectively blocked Bulgaria from siding with the Entente. It was also agreed that Germany was obliged to protect Bulgarian political independence and territorial integrity against attack. In return Bulgaria was obligated by contract to take action against any of its neighbouring states if they attacked Germany. Bulgaria was now committed, it had chosen its side.
Now the whole reason why the French army was to land in the Balkans is quite clear, its main aim was to help the Serbian army which was struggling against the Central Powers (including Bulgarian army). Initially however, the forces sent would be meagre, due to the large-scale assaults happening on the Western Front during this time. They would land at the Greek port of Thessaloniki, however their effectiveness was small.
The French and British divisions marched north from Thessaloniki in October 1915 under the joint command of French General Maurice Sarrail, and Irish General Bryan Mahon (Commander, British Salonika Force, 1915). However, the War Office in London was reluctant to advance too deep into Serbia. So the French divisions advanced on their own up the Vardar River. This advance gave some limited help to the retreating Serbian Army, as the Bulgarians had to concentrate larger forces on their southern flank to deal with the threat, which led to the Battle of Krivolak (October–November 1915). By the end of November, General Sarrail had to retreat in the face of massive Bulgarian assaults on his positions. During his retreat, the British at Kosturino were also forced to retreat. By December 12, all allied forces were back in Greece. The Germans ordered the Bulgarians not to cross the Greek borders, reluctant to risk a Greek entry into the war in response to a Bulgarian invasion in Macedonia. The Allies for their part took advantage of that, reinforcing and consolidating their positions behind the borders
The conflict in the Balkans would end in September 1918 , when finally, the Serbs, British, French and Greeks forces managed to break through on the Macedonian front and Tsar Ferdinand was forced to sue for peace. It is just another chapter in a bloody conflict, I hope it has been useful to learn about, it has certainly been interesting to research!