Battle of Issus
The Persian fleet under Memnon of Rhodes and Pharnabazus was apparently a considerable danger for Antipater, bringing war in the Aegean sea and threatening war in Europe. Luckily for the regent, Memnon died during the siege of Mytilene on the isle of Lesbos and the remaining fleet dispersed in 333 BC, after Alexander's victory at the Battle of Issus.