Advancing from Doberus, the Thracian host first invaded what had been once Philip's government, and took Idomene by assault, Gortynia, Atalanta, and some other places by negotiation, these last coming over for love of Philip's son, Amyntas, then with Sitalces.
Laying siege to Europus, and failing to take it, he next advanced into the rest of Macedonia to the left of Pella and Cyrrhus, not proceeding beyond this into Bottiaea and Pieria, but staying to lay waste Mygdonia, Crestonia, and Anthemus.
The Macedonians never even thought of meeting him with infantry; but the Thracian host was, as opportunity offered, attacked by handfuls of their horse, which had been reinforced from their allies in the interior.
Armed with cuirasses, and excellent horsemen, wherever these charged they overthrew all before them, but ran considerable risk in entangling themselves in the masses of the enemy, and so finally desisted from these efforts, deciding that they were not strong enough to venture against numbers so superior.
Meanwhile Sitalces opened negotiations with Perdiccas on the objects of his expedition; and finding that the Athenians, not believing that he would come, did not appear with their fleet, though they sent presents and envoys, dispatched a large part of his army against the Chalcidians and Bottiaeans, and shutting them up inside their walls laid waste their country.

While he remained in these parts, the people farther south, such as the Thessalians, Magnetes, and the other tribes subject to the Thessalians, and the Hellenes as far as Thermopylae, all feared that the army might advance against them, and prepared accordingly.

These fears were shared by the Thracians beyond the Strymon to the north, who inhabited the plains, such as the Panaeans, the Odomanti, the Droi, and the Dersaeans, all of whom are independent.

It was even matter of conversation among the Hellenes who were enemies of Athens whether he might not be invited by his ally to advance also against them.

Meanwhile he held Chalcidice and Bottice and Macedonia, and was ravaging them all; but finding that he was not succeeding in any of the objects of his invasion, and that his army was without provisions and was suffering from the severity of the season, he listened to the advice of Seuthes, son of Spardacus, his nephew and highest officer, and decided to retreat without delay.