Complex sentence: He was Colonel of the 58th Battalion, Company of London Home Guard during World War II. He was given the rank of Honorary Air Commodore in No.21 (City of Melbourne) Squadron, Royal Australian Air Force.
Split into simpler sentences: He was Colonel of the 58th Battalion, Company of London Home Guard. He gained the rank of Honorary Air Commodore in the service of the No.21 (City of Melbourne) Squadron, Royal Australian Air Force.