Kammala jumla mai zuwa: Alexander an haife shi ne a Landan daga iyayen aristocratic kuma ya yi karatu a Harrow kafin ya koma Kwalejin Soja ta Royal, Sandhurst, don horar da shi a matsayin jami'in soja na Irish Guards. Ya zama sananne ta hanyar hidimarsa a Yaƙin Duniya na Farko, yana karɓar girmamawa da lambobin yabo da yawa, kuma ya ci gaba da aikin soja ta hanyar kamfen ɗin Burtaniya daban-daban a duk faɗin Turai da Asiya. A Yaƙin Duniya na Biyu, Alexander ya kula da matakai na ƙarshe na ƙauracewar Allied daga Dunkirk kuma daga baya ya gudanar da manyan kwamandojin filin a Burma, Arewacin Afirka da Italiya, gami da yin aiki a matsayin Babban Kwamandan Gabas ta Tsakiya da kuma jagorancin rukunin Sojoji na 18 a Tunisia. Daga nan sai ya umurci rundunar sojojin 15th don
kama Sicily da kuma sake a Italiya kafin samun filin marshal ta baton da ake yi Supreme Allied kwamandan Rum.