Who were serbias allicance?

Serbia was a part of no formal alliance until 1912, but its independence was guaranteed by Russia in March 1909 in return for Serbian recognition of Austria-Hungary's annexation of Bosnia-Hercegovina.

In 1912 Serbia joined with Bulgaria, Greece and Montenegro in The Balkan League, with the intention of seizing the Ottoman Empire's European territory and dividing it up between them. Bulgaria went to war against its former allies the following year after being denied its agreed share.