Germans felt necessary for the corridor to Turkey to supply ammunitions. Turks were short of everything and had no capacity to produce shells.

There stood Serbs against them.

The king of Bulgaria, Ferdinand came from the House of Saxe=Coburg=Gotha and had been educated in Austrian cadet school. He was regarded as pro-Germany from the outset. And he was an innate war-lord initiating two Balkan Wars and hoped to change his Kingdom into a kind of Empire. He himself styled Tsar of Bulgaria.

And neighbourhood was alarmed by Bulgarians with their militarily oriented characteristics and they were called Prussians in Balkan.

Bulgaria was courted by both the Allied powers and the Central with the bait of Serbian Macedonia. The Allied failed to persuade Serbian to give up it.

Macedonia was ruled by Serbs but residents were mixed up with Greeks, Turks, Bulgarians and minority Serbs. And the majority of residents wanted to be independent.

Bulgaria decided to side with the Central powers but Bulgarians originally came from the Urals and felt affinity for Russians. Inside Bulgaria a deep chasm ran through.

6, September 1915 Ferdinand made a secret protocol with Germans. In return for Macedonia Bulgaria would enter the War. Bulgaria's population was about 6 million. They declared 520 thousand men could be mobilised This number was largest among Balkan countries. However, the army could not be modern to the extent that meaningful number of soldiers had to go home during the farming season.

King Ferdinand and Kaiser met near Nis.

It is easily imagined that they entered the War in October because it was after harvest season.

Falkenhayn ascended by Bulgarian entry and planned the operation to knock out Serbia and to open up the road to Turkey.

Balkan Offensive

Serbian defence was deployed along River Drina from the memory of the last year's Austrian offensive. Falkenhayn's plan was to set up three divisions for Serbian main defence as a feint and directly to attack Belgrade, Serb's capital by crossing the Danube. The main attacking armies were commanded by von Mackenzen. These armies consisted of Austrian 11th army (Gallwitz) and German 11th (Koebes).

Bulgarians also divided up their force into two armies, one for Salonica and the other for Nis, Serbian provisional capital. Falkenhayn also mixed into Mackenzen's four divisions which were to be transferred from the east to the west. These four were conveniently added to the attacking armies.

This meant the Allied offensives on the western front were not effective. Serbian, feinted by Drina crossing failed to counterattack Mackenzen's main force.

Map; Balkan Offensive

On 12, October Mackenzen army(then, called) successfully crossed the Danube and the same day the
street fighting in Belgrade took place. Serbs already lost logistics and ammunitions ran out.

Bulgarians also crossed Serbian eastern border on 10, October, four days before the official declaration of war.

In Greece there arose severe disputes between king's faction,pro-the Central powers and prime minister's, pro-the Allied. After all they decided to keep neutral. French did not care about Greek neutrality and sent troops to Salonica. CinC Sarraill arrived there 12, October and then brought all troops to the north. However, the enemy was fresh Bulgarians and the prospective battlefield was mountainous. It was hard to contact Serbs attacked from three directions.

Mackenzen's march was very slow like when Gorliz break through. Because even Mackenzen felt difficult to speed up due to geography and Serb's hard resistance. Bulgarians were more exuberant than Germans and Austrians. They rushed to divide the whole territory of Serbia making a salient shaped like a wedge. 12, October they reached the mountain area of the central Macedonia and it became impossible for Serbs and French to get contact with.

On 5, November the Central force occupied Nis, which meant an access to Constantinople.

Serbs were not terribly damaged so far and decided the final battle in mountain areas under the command of Putnik, chief of general staff. Serbia fought desperate and final resistance against Germans and Austrians at Pristina and Mitrowica in Kosobo and against Bulgarians at Plateau Black Birds.

After these battles Putnik ordered general retreat. All automobiles and heavy guns were abandoned and the aged king was drawn by oxen cars. All troops, government officials and even foreign diplomats entered mountainous and snowy Albania harassed by bandits.

Retreating Serbian

300 thousands fled to the seashore of Aegean Sea taking one month and half with 20 thousands lost. They were rescued by Italian and French flotillas and taken to Island Corf and then, joined French in Salonica.

In this winter the Central countries were also annoyed by the dispute between Conrad and Falkemhayn. Conrad insisted on the immediate occupation of MonteNegro and pursuit of Serbian field army. Falkenhayn opposed speaking the winter season, the geography and the violation of Albanian neutrality. Conrad decided the attack even by Austrians only.

They entered MonteNegro January 1916 and occupied it with perfect destruction of the regime. It was one of few successful campaigns planned by Conrad.

The Allied troops in Salonica had been reinforced to almost 300 thousand till 1918. Though, Bulgarians were losing fighting spirit gradually. French were also hard up to march to the Southern Macedonia geographically. Germans called French occupied Salonica as the largest intern camp but at the final phase of the First World War it would play the important role.