Volagases III died in 191 A.D., having reigned forty-two years without civil war, and was succeeded by Volagases IV, who fought several vain battles with Rome. In 199 A.D. a fleet on the Euphrates co-operated with the Roman army, and Severus, taking up an unaccomplished plan of Trajan, dredged out the old Naarmalca canal, through which his ships sailed into the Tigris, and took the Parthians wholly by surprise. Seleucia and Coche were deserted by their inhabitants; Ctesiphon was taken by the end of the year with terrible slaughter, one hundred thousand inhabitants being led captive and the place given up to pillage, for the Great King had fled powerless at the approach of the foe. Severus, whose force was reduced by famine and dysentery, did not attempt pursuit, but drew off up the Tigris. The army was again in its quarters by the 1st of April, 200 A.D., and for some time thereafter Severus was occupied in Armenia. But in 201 A.D. he undertook a carefully organised expedition against Atra, from whose walls the Romans had been repulsed with great loss when Severus, returning from the Tigris in the previous year, had attempted to carry it by a _coup de main_. This city, which in Trajan’s time was neither great nor rich, was now a wealthy place, and the sun temple contained vast treasures. The classical authors call it Arabian, but the king’s name is Syriac--Barsenius, _i.e._, Bar Sín, son of the moon, and we may suppose that it was really an Aramæan principality, which like Palmyra had its strength from the surrounding Arab tribes that it could call into the field. Severus lay before Atra for twenty days, but the enemy’s cavalry cut off his foraging parties, the admirable archers galled the Roman troops, a great part of the siege-train was burned with naphtha; and when, in addition, two assaults had been repulsed with tremendous loss on two successive days, the emperor was compelled to raise the siege--a severe blow to Roman prestige in the East, and one that greatly exalted the name of Atra and its prince, but did not help in the least the decaying power of Parthia.