 He quickly applied for a commission, and spent three years serving mainly in the Army Service Corps.In 1917 he applied to join the Royal Flying Corps and learned to fly in Cairo; he gained his wings in 1918.In 1919 Chibnall was taken on by Professor H B Baker to do research for the newly-instituted PhD at Imperial College, but he later switched to study the nitrogenous constituents of green leaves with Professor S B Schryver, whom he succeeded in 1929.