Complex sentence: His father served as a hostage in the court of Eastern Roman Emperor Diocletian in Nicomedia, thus securing the loyalty of Caesar of the Western Roman Empire Constantius Chlorus, father of Constantine and grandfather of Crispus.
Split into simpler sentences: His father served as a hostage in the court of Eastern Roman Emperor Diocletian in Nicomedia. Thus securing the loyalty of Caesar of the Western Roman Empire Constantius Chlorus, father of Constantine and grandfather of Crispus.