Ka kammala wannan magana: A lokacin Yaƙin Duniya na II, ya umurci rundunar bindigogi. Ya jagoranci bindigogi a ƙasashen waje yayin mamayewar Allied na Sicily a watan Yuli-Agusta 1943, inda ya sami na farko na Gicciye Biyu na Musamman. Ya ci gaba da jagorantar bindigogi a cikin mamayewar Allied na Italiya a watan Satumba, kuma a farkon matakan yakin Italiya, kafin a tura shi zuwa Ingila. A lokacin yakin Normandy a watan Agustan 1944, McLain ya dauki umurnin 90th Infantry Division, wanda ke da matsaloli masu yawa. McLain ya canza 90th zuwa wani nau'i na farko na yaki, kuma ya jagoranci shi a fadin Faransa a
Ƙungiyar Allied ta ci gaba daga Paris zuwa Rhine kuma a cikin yawancin yaƙe-yaƙe a Western Front. A watan Oktoba sai ya karbi umurnin XIX Corps, ya kasance kwamandansa har zuwa karshen yakin. Shi ne kawai mai tsaron gida wanda ya jagoranci rundunar soja a lokacin yakin duniya na biyu.