As a young officer, Rowell served at Gallipoli but was invalided back to Australia with typhoid fever in January 1916. The end of the war found Rowell junior in rank to his contemporaries with more distinguished war records, but he managed to catch up in the post-war period. Rowell spent five years with the British Army or at British staff colleges, establishing valuable contacts with his British counterparts. In 1939 he was appointed chief of staff of the 6th Division and later I Corps, serving in that capacity in the Battle of Greece and the Syria-Lebanon campaign. In 1942 he commanded I Corps in the Kokoda Track campaign but was sacked. His subsequent rise to become Chief of the General Staff demonstrated that the circumstances of his dismissal in 1942 were indeed extraordinary.