Prusias II Cynegus was the king of Bithynia

Bithynia

Bithynia was an ancient region, kingdom and Roman province in the northwest of Asia Minor, adjoining the Propontis, the Thracian Bosporus and the Euxine .-Description:...

. He was the son and successor of Prusias I

Prusias I of Bithynia

Prusias I Cholus was a king of Bithynia...

 and Apama III

Apama III

For other uses of this name see, Apama Apama III, sometimes known as Apame III was a Greek Princess from the Antigonid dynasty....

.

Prusias joined with King of Pergamon, Eumenes II

Eumenes II

Eumenes II of Pergamon was king of Pergamon and a member of the Attalid dynasty. The son of king Attalus I and queen Apollonis, he followed in his father's footsteps and collaborated with the Romans to oppose first Macedonian, then Seleucid expansion towards the Aegean, leading to the defeat of...

 in a war against King Pharnaces I of Pontus

Pharnaces I of Pontus

Pharnaces I , fifth king of Pontus and was of Persian and Greek Macedonian ancestry. He was the son of King Mithridates III of Pontus and his wife Laodice, whom he succeeded on the throne. Pharnaces had two siblings: a brother called Mithridates IV of Pontus and a sister called Laodice who...

 (181–179 BC). He later invaded the territories of Pergamon

Pergamon

Pergamon , or Pergamum, was an ancient Greek city in modern-day Turkey, in Mysia, today located from the Aegean Sea on a promontory on the north side of the river Caicus , that became the capital of the Kingdom of Pergamon during the Hellenistic period, under the Attalid dynasty, 281–133 BC...

 (156–154 BC), only to be defeated, and the Pergamenes insisted on heavy reparations. Prusias married his maternal niece and maternal half-cousin Apame IV

Apame IV

For other uses of this name see, Apama Apame IV, sometimes known as Apama IV was a Macedonian princess from the Antigonid dynasty. Her father was Philip V, King from 221 BC to 179 BC, her mother was his first wife the daughter of Prusias I Cholus and Apama III, and her half-brother was Perseus,...

, a princess from the Antigonid dynasty

Antigonid dynasty

The Antigonid dynasty was a dynasty of Hellenistic kings descended from Alexander the Great's general Antigonus I Monophthalmus .-History:...

, by whom he had a son called Nicomedes II and a daughter, also called Apama, born c. 175 BC, who married Prince Dyegilos of Thrace

Thrace

Thrace is a historical and geographic area in southeast Europe. As a geographical concept, Thrace designates a region bounded by the Balkan Mountains on the north, Rhodope Mountains and the Aegean Sea on the south, and by the Black Sea and the Sea of Marmara on the east...

, born c. 180 BC. He sent his son Nicomedes II to Rome

Roman Republic

The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...

 to ask their help in reducing the amount of these reparations, but Nicomedes revolted and became King.

Towards the end of his life, Prusias II had children by a later wife, and wanted to make them his heirs in place of Nicomedes, son of his earlier wife. Prusias even tried to arrange his eldest son Nicomedes murdered. Nicomedes however revolted against his father. Prusias had to renounce the kingship in favor of his son and ended up being murdered himself instead.