hackett junior received secondary schooling at geelong grammar school in victoria and then travelled to london to study painting at the central school of art. he then studied greats and modern history at new college, oxford, earning an m.a. as his degree was not good enough for an academic career, hackett joined the british army and was commissioned into the 8th king's royal irish hussars in 1933, having previously joined the supplementary reserve of officers in 1931. during his military training, he completed a thesis in history with a focus on the crusades and the early middle ages, particularly saladin's campaign in the third crusade, for which he was awarded a b. litt. he also qualified as an interpreter in french, german and italian, studied arabic and eventually became fluent in ten languages.