Demetrius II
Diodotus was originally from , a dependent town of the city of Apamea. He served as a general for Alexander Balas, during the civil war which the latter fought with Demetrius II Nicator. In 145 BC, when Alexander's father-in-law Ptolemy VI of Egypt switched his support to Demetrius II and invaded Syria, Diodotus and a man called Hierax were in command of the city of Antioch. They surrendered Antioch to Ptolemy and declared him king of the Seleucid Empire. Ptolemy, unwilling to rule both the Egyptian and Seleucid realms directly, declined the title in favour of Demetrius II.