Complex sentence: After the death of Seleucus, Patrocles was sent by his successor Antiochus to put down a revolt in Asia Minor, but there his forces were defeated in an engagement with the Bithynians.
Split into simpler sentences: After the death of Seleucus, Patrocles was sent by his successor Antiochus to put down a revolt in Asia Minor. However his forces were defeated there in an engagement with the Bithynians.