Ptolemy IV Philopator
Descended from an illustrious family from Argos, Polycrates joined the court of the Egyptian monarch Ptolemy IV Philopator, just before his campaign against Antiochus III in 217 BC. He was of great service in drilling and encouraging the Egyptian troops, and he commanded the cavalry on the left wing at the battle of Raphia, in which Antiochus was defeated, and which secured for Ptolemy the provinces of Coele-Syria, Phoenicia, and Palestine.