Complex sentence: Antigonus II Gonatas invaded Thrace in the summer of 277 and defeated a large force of 18,000 Gauls, he was quickly hailed as king of Macedon and ruled for 35 years.
Split into simpler sentences: Antigonus II Gonatas invaded Thrace in the summer of 277 and defeated a large force of 18,000 Gauls. He was quickly hailed as king of Macedon and went on to rule for 35 years.