Kammala jumla mai zuwa: An ba Callinan mukamin Laftanar a cikin Sojojin Citizens a watan Yunin 1940, an nada shi a cikin Injiniyoyin Australiya na Royal. A watan Maris na 1941, ya ba da kansa don yin aiki a ƙasashen waje kuma ya shiga rundunar sojojin Australiya ta biyu, inda ya zama mai koyarwa a cikin Demolitions Wing, a Cibiyar Horar da Sojoji ta 7. An daukaka shi zuwa kyaftin a watan Yulin 1941, kuma daga baya aka tura shi a matsayin mataimakin kwamandan zuwa &lt;a href="2/2nd%20Commando%20Squadron%20%28Australia%29"&gt;2/2nd Independent Company&lt;/a&gt;, tare da tura su zuwa
Timor a matsayin wani ɓangare na Sparrow Force a watan Disamba na 1941. Daga baya ya jagoranci kwamandojin a lokacin yakin da suka yi a tsibirin kuma a watan Yulin 1942 an ba shi mukamin Manjo na ɗan lokaci.