 Hawker was educated at Geelong Grammar School, and Trinity College, Cambridge, earning Bachelor and Master of Arts degrees in 1919 and 1922, respectively.While studying at Cambridge, he enlisted for service in World War I on 11 August 1914, and was commissioned as a temporary lieutenant in the 6th (Service) Battalion of the Somerset Light Infantry on 1 August 1915.He saw action on the Western Front in the Ypres salient, and was injured on 11 August and again in the Battle of Loos on 25 September, resulting in the loss of his eye.