Faatumu le fuaiupu lenei: O le 21st Army Group o le Taua Lona Lua a le Lalolagi o se faʻavaeina o le ofisa tutotonu a Peretania, i le faʻatonuga a le lua autau a le fanua ma isi vaega lagolago, e aofia ai ma le British Second Army ma le First Canadian Army. Na faavaeina i Lonetona i le masina o Iulai 1943, i lalo o le faatonuga a le Supreme Headquarters Allied Expeditionary Force (SHAEF), na tofia i le Operation Overlord, le
Na avea o ia ma vaega tāua o le ʻautau a le ʻau Uelese i Europa. I taimi eseese i le taimi o lona olaga, o le 21st Army Group sa i ai ni isi autau a Peretania, Kanata, Amerika ma Polani. O le 21st Army Group sa galue i Northern France, Luxembourg, Belgium, Netherlands ma Siamani mai ia Iuni 1944 seʻia oʻo ia Aukuso 1945, ina ua toe faʻaigoaina o le British Army of the Rhine (BAOR).