Mithradates, who from the Crimea maintained connections with the Thracians, was hardly a stranger to all these events.

The praetor Gaius Sentius defended himself, it is true, against these intruders with the aid of the Thracian Dentheletae; but it was not long before mightier opponents came against him.
Mithradates, carried away by his successes, had formed the bold resolution that he would, like Antiochus, bring the war for the sovereignty of Asia to a decision in Greece, and had by land and sea directed thither the flower of his troops.

His son Ariarathes penetrated from Thrace into the weakly-defended Macedonia, subduing the country as he advanced and parcelling it into Pontic satrapies.
Abdera and Philippi became the principal bases for the operations of the Pontic arms in Europe.

The Pontic fleet, commanded by Mithradates' best general Archelaus, appeared in the Aegean Sea, where scarce a Roman sail was to be found.

Delos, the emporium of the Roman commerce in those waters, was occupied and nearly 20,000 men, mostly Italians, were massacred there; Euboea suffered a similar fate; all the islands to the east of the Malean promontory were soon in the hands of the enemy; they might proceed to attack the mainland itself.