 Nyorera kupfuurira kweiyi ndima - Kutevera kutanga kweHondo Yenyika Yekutanga, Blacklock akadzokera kuEngland kunobatanazve nechikwata chake chekare uye nekukurumidza akawana kukwidziridzwa. Akashanda semukuru mukuru we10th Battalion yeKings Royal Rifle Corps kubva muna Zvita 1915. Akaenderera mberi kuva mutungamiri we 182nd 21st Warwickshire Brigade muna 1916 uye ipapo mutungamiri we 97th Brigade muna 1917. Akakuvadzwa muHondo yeGuillemontmuna September 1916 uye akapiwa Bar kune Distinguished Service Order nokuda kwezviito zvake. Akagadzwa General Officer Commanding 9th Scottish Division muna Kurume 1918 uye General Officer Commanding 39th Division gare gare mwedzi iwoyo. Pachinzvimbo ichi akatarisira kudzivirirwa kwakasimba kwe39th Division yeSomme mukutarisana neGerman spring offensive. Zvichitevera kudzingwa basa kweDivision kubva kumberi, Blacklock akaitwa General Officer Commanding 63rd Royal Naval Division muna Nyamavhuvhu 1918. Mukuru wake mukuru, Mukuru Mukuru Sir Charles Fergusson aiona Blacklock somutungamiriri akanakisisa waakanga amboona. Blacklock akagamuchirawo kurumbidzwa kwevamwe vatungamiriri vakuru vehondo yekuraira kwake, kusanganisira General Horne uye Field Marshall Haig. 