Cause:
In February 1912 a treaty was concluded between Bulgaria and Serbia, whereby it was agreed that North-west Macedonia should go to Serbia, another part to Bulgaria, and the zone lying between these two should be submitted to the arbitration of the Czar. In December 1912, in the First Balkan War, Austria protested against the occupation by Serbia of Durazzo on the Adriatic, and of Scutari by Montenegro. Serbia declared that Bulgaria did not adequately support her in resisting the Austrian demand, felt impelled to claim more territory in Macedonia, and refused to carry out the provisions of the treaty with Bulgaria. Serbia was ready to arbitrate. Russia was inclined to support the Serbian claim. Bulgaria hesitated.