With the Rhodian fleet and economy suffering from the depredations of the pirates, Philip believed his chance to crush Rhodes was at hand. To help achieve his goal, he formed an alliance with the King of the Seleucid Empire, Antiochus the Great, against Ptolemy V of Egypt (the Seleucid Empire and Egypt were the other two Diadochi states). Philip began attacking the lands of Ptolemy and Rhodes's allies in Thrace and around the Propontis.