 Akagadzwa semukuru mukuru we9th Infantry Division muna 1913, uye akaitungamirira kusvika muna 1916, paakabatana neVenizelist Movement of National Defense muThessaloniki, iyo, ichipesana nehurumende yeumambo muAthens, yakapinda Hondo Yenyika I kudivi reEntente Powers. Ioannou akapiwa basa rokuumba Dhipatimendi reArchipelago, rakatorwa kuvagari vezvitsuwa zveAegean. Pakazosvika May 1917, divi rake rakanga rakagadzirira uye rakagoverwa muMonastir sector yeMacedonian front. Akatungamirira boka rake kukunda muhondo yeSkra-di-Legenmuna May 1918, uye vakabatanidzwa nayo mukurwisa kwakazara kweAllied kwaSeptember 1918, uko kwakaputsa nhandare yeGerman-Bulgarian. Chibvumirano chokurwisana neBulgaria chakamuwana aine boka rake paPehčevo. 