Ptolemy IV was the second child and eldest son of Ptolemy III and his wife Berenice II. He was born about two years after his father's accession to the throne of Egypt. Ptolemy IV had an older sister, Arsinoe III, and three younger brothers, Lysimachus (name uncertain), Alexander and Magas, all born in the 240s BC. The whole family is commemorated by a statuary groups set up at Thermos and Delphi by the Aetolian League. Under Ptolemy III, the Ptolemaic kingdom had reached its height, decisively defeating the rival Seleucid kingdom in the Third Syrian War (246–241 BC), financing mainland Greek opposition to Antigonid Macedonia, and maintaining control of nearly the entire eastern Mediterranean seaboard. However the reign was also marked by the first native Egyptian revolt against Ptolemaic rule, in 245 BC. In the final years of Ptolemy III's reign, the Cleomenean War (229–222 BC) broke out in Greece and, despite receiving substantial Ptolemaic support, Cleomenes III of Sparta had been completely defeated by an Antigonid-led coalition and forced to flee to Egypt.