Kammala jumla mai zuwa: A lokacin Yaƙin Duniya na Biyu, Hakewill-Smith ya yi aiki a matsayin Kwamandan Kwamandan (CO) na 5th Battalion, Devonshire Regiment, na watanni da yawa daga Mayu 1940 kuma, daga Satumba na wannan shekarar, a matsayin CO na 4th/5th Battalion, Royal Scots Fusiliers, a matsayin mukaddashin Laftanar Kanar. An daukaka shi zuwa brigadier na wucin gadi a ranar 30 ga Maris, 1941, kuma ya umurci Brigade na 157 na Infantry har zuwa ƙarshen Maris 1942. Daga nan sai ya zama Daraktan Kungiya a Ofishin Yakin, kafin ya dauki umurnin 155th Infantry Brigade a tsakiyar watan Fabrairun 1943. A ranar 26 ga Disamba, an ba shi mukamin babban janar na wucin gadi, ya karbi umarnin rundunar soja ta 52 (Lowland) da aka horar da ita daga Manjo Janar Neil Ritchie a matsayin Babban Jami'in Kwamandan. Ya umurci rundunar 52 a lokacin
yakin da aka yi a Arewa maso Yammacin Turai daga Oktoba 1944 zuwa Mayu 1945.