Complex sentence: He returned back to the military service at the same time when he bace a lecturer at Ain Shams University then he was promoted to be the commander of the third field army during October War when he commanded the 7th Mechanized Division crossing the Suez Canal.
Split into simpler sentences: He returned back to the military service at the same time that he became a lecturer at Ain Shams University. He was then promoted to be the commander of the third field army during the October War when he commanded the 7th Mechanized Division crossing the Suez Canal.