The causes of the Emperor Trajan's campaign to conquer Parthia once and for all included: Please chose one of the answers below: King Chosroes of Parthia supporting Parthamisiris for king of Armenia against the Roman candidate, Axidares, violating a previous treaty. Roman control of Mesopotamia (modern Iraq) would give the empire access to the Persian Gulf and trade with India. Trajan wished to emulate Alexander the Great. or All of the above.

The causes of the Emperor Trajan's campaign to conquer Parthia once and for all included: Please chose one of the answers below: King Chosroes of Parthia supporting Parthamisiris for king of Armenia against the Roman candidate, Axidares, violating a previous treaty. Roman control of Mesopotamia (modern Iraq) would give the empire access to the Persian Gulf and trade with India. Trajan wished to emulate Alexander the Great. or All of the above.