Rubuta ci gaba don wannan sakin layi - Daga Eton, Grigg ya shiga rundunar sojan Burtaniya kuma an ba shi izini a matsayin laftanan na biyu a cikin rundunar mahaifinsa, Grenadier Guards, a cikin 1943 a lokacin Yaƙin Duniya na Biyu (1939<unk>1945). Yayin da yake cikin Sojojin Burtaniya, Grigg ya yi aiki a matsayin jami'in Tsaro a Fadar St James da Windsor Castle, Berkshire, kuma ya ga aikin a matsayin kwamandan kwamandan a cikin 1st Battalion, Grenadier Guards, wani ɓangare na 5th Guards Armored Brigade na Gardi Armored Division, a kan sojojin Jamus a Faransa da Belgium
Ka yi haƙuri. A karshen yakin, ya zama jami'in leken asiri.