Rubuta ci gaba don wannan sakin layi - Bayan yakin, Mackay ya yi karatun kimiyyar lissafi a Jami'ar Cambridge a karkashin Ernest Rutherford kafin ya koma Ostiraliya da kuma tsohon aikinsa a matsayin malami a Jami'ar Sydney. Daga 1933 zuwa 1940 ya kasance darektan makarantar Cranbrook, Sydney. Ya kasance a cikin Militia tsakanin yaƙe-yaƙe, kuma ya kasance babban janar a lokacin da Yaƙin Duniya na Biyu ya ɓarke. An zaba shi ya zama kwamandan na 6 a 1940, kuma ya jagoranci shi ta hanyar yakin farko na sojojin Australia na yakin. Duk wani shakku game da ikonsa ya ɓace tare da sadaukar da kai ga Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙungiyar Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun Ƙwararrun. A lokacin yakin Bardia
a watan Janairun 1941, Rundunar ta 6 ta kama garin da ke da karfi tare da fursunonin Italiyanci 36,000. A cikin yakin Girka, ya zama babban janar na Australiya wanda ya fuskanci "Waffen-SS" a yaƙi. Ya sha wahala jerin koma baya a Girka, amma ya burge sojojin da ke karkashin umurninsa tare da jaruntakarsa a karkashin wuta. An sake kiran shi zuwa Ostiraliya a 1941 don yin aiki a matsayin Janar Janar Janar Janar. A ranar 6 ga Afrilu 1942, ya karbi umarnin rundunar soja ta biyu. A lokacin 1943 ya yi umurni sau biyu a New Guinea Force a cikin fadace-fadace a yakin New Guinea. Ayyukansa na aiki ya ƙare tare da nadinsa a matsayin Babban Kwamishina zuwa Indiya a watan Nuwamba 1943.