 Nyorai kupfuurira kweiyi ndima - Apo Hondo yeNyika II yakatanga, McKinnon akanga ari muEngland pamusangano wokurovedza pfuti. Akabatana neChipiri New Zealand Expeditionary Force uye akashanda ne3rd New Zealand Division panguva yemushandirapamwe muSolomon Islands. Pakutanga akanga ari mutungamiri we28th Heavy Anti-Aircraft Regiment asi apo chikwata chake chakaparadzaniswa muna July 1942 akatora 29th Light Anti-Aircraft Regiment. Navarwi vake, akaburuka paTreasury neGreen Islands. Apo boka racho rakadzingwa basa muna 1944, akadzokera kuEngland kunopinda Staff College kuCamberley. Pashure pokupedza kosi yake yevashandi, akabatana ne2nd New Zealand Division, panguva iyoyo achirwa muItaly neEighth Army, pamwe chete nevamwe vakuru vehondo vakanga vashumira muPacific. Paakasvika muItaly muna February 1945, akanga ari wechipiri-mu-mutungamiri wekutanga 4th Field Regiment uye ipapo 6th Field Regiment. 