The expedition against Persia had been long in the works, and Alexander did not make it a secret that he planned to avenge the attacks on Greece by Persia a century and a half before, despite that at the time his kingdom had been a Persian vassal state. It was as a result of this planned expedition that King Darius III started to distribute money to the Greek city-states with the hope that they would rise against their new Hegemon. In addition to this, he had sent his most able general Memnon of Rhodes against the Macedonian troops that were already stationed in Ionia at this time.