Whakaotihia te rerenga e whai ake nei: I te pakarutanga o te pakanga i te marama o Hepetema 1939, ka whakauruhia te ope taua ki te tiaki i nga rohe nui huri noa i te taone nui. I te tau 1940 i tohua te 1st Battalion o te puhi kia haere ki tawahi. I hangaia a Rockingham hei Kapene, engari i korerotia ki a ia mena e hiahia ana ia ki te haere me te roopu, me hoki ia ki tana tuunga o mua o Lieutenant, i kowhiria e ia kia mahia. I haere te ope ki Halifax mai i reira ka rere ki Glasgow, a, i muri tata mai i te taenga mai ka whakawhiti atu ki Aldershot. I reira, i tohua a Rockingham hei rangatira mo te kaitiaki honore mo Kingi George VI me Kuini Elizabeth, i toro atu i tera Tihema. I muri mai ka tukuna ia ki te kura whakahau a te kamupene o Canada. I te kura a Rockingham i te wā i whakahaeretia ai e Kanata te
Te whakaekenga o Dieppe i te 19 o Akuhata 1942. He waahanga nui o te Royal Hamilton Light Infantry i mate i te wa o tenei whakaekenga, a ka tukuna a Rockingham ki te rerenga kua pau hei Major. I tohaina ki te takutai tonga o Ingarangi hei waahanga o te kaha whakaeke-a-roto, i te 14 o Paenga-whawha 1943 i whakatairangahia a Rockingham ki a Lieutenant-Colonel ka waiho hei Kaiwhakahaere Whakahaere mo te ope. I te 19 o Hui-tanguru 1944, i whakaorangia a Rockingham i tana whakahau, a ka tukuna ki te Whare Wananga o nga Kaimahi, Camberley mo te whakangungu atu. Whai muri i te whakaekenga o Normandy i te 6 o Pipiri 1944, ka haere te RHLI ki Parani me te kore o Rockingham. Heoi, i tere te whara o to ratou rangatira. I nekehia a Rockingham mai i te Whare Wananga o nga Kaimahi, a i te 18 o Hurae i whakawhiwhia ki te rangatira o te Rōpū ano ka tukuna ki Parani.