The Battle of the River Amnias was a battle fought in 89 BC between Mithradates VI of Pontus and Nicomedes IV of Bithynia during the First Mithridatic War. The forces of Pontus were commanded by Archelaus and Neoptolemus, while the Bithynians were led by king Nicomedes himself. Pontus was victorious. This battle and subsequent events would lead to the loss of Roman rule in the province of Asia for some years.