Rubuta ci gaba don wannan sakin layi - Serbia ta yi yaƙi a Yaƙe-yaƙe na Balkan na 1912<unk>13, wanda ya tilasta Ottomans daga Balkans kuma ya ninka ƙasa da yawan mutanen Masarautar Serbia. A shekara ta 1914, wani matashi ɗalibi Ba-Serb mai suna Gavrilo Princip ya kashe Archduke Franz Ferdinand na Austria, wanda hakan ya sa aka soma Yaƙin Duniya na I. A yaƙin da ya biyo baya, Austria-Hungary ta kai wa Serbia hari. Duk da cewa sun fi yawa, daga baya Serbs sun ci Austro-Hungarians a yakin Cer, wanda ya nuna nasarar farko ta Allied a kan Tsakiyar Tsakiya a cikin yakin. Karin nasarori a yakin Kolubara
kuma Drina yana nufin cewa Serbia ta kasance ba a ci nasara ba yayin da yakin ya shiga shekara ta biyu. Koyaya, mamayewa daga sojojin Jamus, Austria-Hungary da Bulgaria sun mamaye Serbia a cikin hunturu na 1915, kuma janyewar da Sojojin Serbia suka yi ta hanyar Albania ya ɗauki rayukan Serbs sama da 240,000. Sojojin Serbia sun kwashe sauran shekarun yakin suna fada a gaban Salonika a Girka, kafin su 'yantar da Serbia daga mamayar Austro-Hungary a watan Nuwamba 1918.