Rubuta ci gaba don wannan sakin layi - Oglethorpe sai ya tafi Faransa, inda 'yan uwansa mata Anne da Fanny suka zauna, ya halarci makarantar soja a Lompres, kusa da Paris, inda ya sadu kuma ya yi abokantaka da abokin karatun James Francis Edward Keith. A shekara mai zuwa, da niyyar yin yaƙi a Yaƙin Austro-Turkish, ya yi tafiya don yin aiki a ƙarƙashin kwamandan soja Prince Eugene na Savoy. Tare da wasiƙar shawarwari daga Duke na Argyle da wasu fitattun 'yan Burtaniya, Oglethorpe da Louis François Crozat sun isa kuma tare da Infante Manuel, Count of Ourém ya shiga aikin Yarima a ranar 3 ga Agusta a matsayin mai taimakawa. Oglethorpe ya kasance a yakin Petrovaradin
a watan Agusta 1716, kodayake ba a tsunduma cikin aiki ba, a Siege of Timisoara a watan Satumba na wannan shekarar ya yi aiki a matsayin mataimakin soja. Ya sami umarni mai aiki a Siege na Belgrade, daga 19 ga Yuni zuwa 16 ga Agusta. Bayan mutuwar shugabansa a cikin yaƙi, a ranar 16 ga Agusta, Oglethorpe a matsayin babban jami'in mai kula da sansanin ya yi aiki a matsayin babban jami'in janar; a matsayin haka ya mallaki sansanin Turkiyya, kuma ya ba da rahoto ga Yarima rahoton asarar rayuka. Bayan yakin, an ba shi mukamin Laftanar Kanal a cikin sojojin, wanda bai taɓa karɓa ba.