Complex sentence: His regiment served in Greece and Crete from March to May 1941 before returning to Australia in August 1942, when he was given command of the 3rd Artillery Division and promoted temporary brigadier.
Split into simpler sentences: His regiment served in Greece and Crete from March to May 1941. He returned to Australia in August 1942, where he was given command of the 3rd Artillery Division and promoted temporary brigadier.