Promoted to Major General, he led his division in the First Balkan War, where he lost one of his sons, Spyridon, during the Battle of Bizani (his second son Angelos fell in the Asia Minor Campaign in 1922). Kallaris led the 2nd Division in the Second Balkan War as well, first in the attack against the Bulgarian garrison in Thessaloniki and thereafter in the battles of Kilkis and Kresna.