Prusias was a vigorous and energetic leader; he fought a war against Byzantium (220 BC), seizing its Asiatic territory, a part of Mysia that had been in its possession for a long time.[1] Then, he defeated the Galatians who Nicomedes I had invited across the Bosphorus to a territory called Arisba, putting to death all of their women and children and letting his men plunder their baggage.[2]
At some point during his reign, he formed a marriage alliance with Demetrius II of Macedon, receiving the latter's daughter, Apama, as his wife.
He expanded the territories of Bithynia in a series of wars against Attalus I of Pergamum and Heraclea Pontica on the Black Sea, taking various cities formerly owned by the Heracleans, renaming one of them, Prusias, after himself.[3] While besieging the city of Heraclea Pontica,[4] he dealt many casualties to the besieged,[5] but while climbing a ladder, he was hit with a stone and he broke his leg; the siege was lifted due to his injury.[6] This is likely where he was given the surname "the lame".[7] Philip V of Macedon granted him the ports of Keios and Myrleia in 202 BC, which he renamed Prusias and Apameia[8] respectively. Although he granted sanctuary to Hannibal, who successfully employed an odd stratagem against the Attalids for him at sea,[9] he remained neutral during the Roman Republic's war with Antiochus III the Great, refusing an alliance with Antiochus.[10] He agreed on peace terms with presumably Eumenes II in 183 BC, in the city of Cyzicus.[11] Apama bore Prusias I a son called Prusias II, who succeeded him.
The town of Prusa (now Bursa in Turkey), which he rebuilt, is named after Prusias.