[2] In 342 BC, Philip led a great military expedition north against the Scythians, conquering the Thracian fortified settlement of Eumolpia which he renamed after himself, Philippopolis (modern-day Plovdiv).

The city stood on a peninsula, connected to the land by a 200 yard wide heavily fortified isthmus.

The Athenian navy, under the control of Chares of Athens, kept the Macedonians out of the seas and helped maintain naval superiority.

In the late summer of 340 BC, he led half of his army to Byzantium, but the city refused to surrender to him and prepared to resist.

Most of the Byzantian army was still at Perinthus, but the defenders who remained at Byzantium managed to survive the initial attack.

After several weeks of laying siege to Byzantium, Philip decided to launch one last surprise assault on the walls, using nothing but moonlight to aid the night attack.