Whakaotihia te rerenga e whai ake nei: Ko te 21st Army Group he hanganga tari matua o Ingarangi i te Pakanga Tuarua o te Ao, i te rangatira o nga ope taua e rua me etahi atu waahanga tautoko, ko te nuinga o te Ope Taua Tuarua o Ingarangi me te Ope Taua Tuatahi o Canada. I whakatūria ki Rānana i te Hōngongoi 1943, i raro i te mana o Supreme Headquarters Allied Expeditionary Force (SHAEF), i whakaritea ki Operation Overlord, te
Ko te whakaekenga o te Hauauru o te Hauauru o Uropi, a he kaha nui a Allied i te Whare Taonga o Europi. I nga wa rereke i te wa o tona oranga, ko te 21 Army Group he nui atu o nga ope a Ingarangi, Kanata, Amerika me Polani. I whakahaerehia te 21 Army Group i te Raki o Parani, Luxembourg, Belgium, Netherlands me Tiamana mai i te Pipiri 1944 tae noa ki Akuhata 1945, i te wa i whakaingoatia ai te British Army of the Rhine (BAOR).