Which Parthian king defeated the Roman army led by Mark Antony in 36 BCE?

Phraates IV was the Parthian king who defeated Mark Antony’s Roman army during its invasion in 36 BCE.

Phraates IV ruled the Arsacid, or Parthian, Empire from about 37 to 2 BCE. Antony invaded Parthia from Armenia with a large force, aiming to reverse Rome’s earlier defeat at Carrhae. The campaign failed when Parthian attacks and logistical problems forced the Romans to retreat.

Parthian forces used mobile cavalry, including heavily armored cataphracts and mounted archers. Their harassment of the Roman column caused severe losses during the withdrawal, although the Romans avoided total destruction.

This event is sometimes confused with the Battle of Carrhae in 53 BCE, when the Parthian commander Surena defeated Marcus Licinius Crassus. Carrhae occurred under Orodes II; Antony’s failed invasion took place under Phraates IV.