 Complete the following phrase:  In 114 AD, the Emperor Trajan occupied the city for a couple of years: the Third Cyrenaica legion erected a Triumphal Arch to the west of the Gate of Palmyra. Upon the death of Trajan in 117, Rome relinquished Mesopotamia to the Parthians. Dura was retaken by the Roman army of Lucius Verus during the 