The reigns of _Valerian_ (253-260) and of his associate and successor, _Gallienus_ (260-268), were marked by continuous disaster. Numerous independent rulers--"the thirty tyrants"--established themselves, generally for a very short time, in different regions. In the East, one kingdom, the capital of which was _Palmyra_, and which had for a ruler _Zenobia_, the widow of its founder, lasted for ten years (264-273). The _Goths_ occupied _Dacia_, and from the Cimmerian Bosphorus sent out their predatory expeditions in all directions, plundering cities, including _Athens_ and _Corinth_, and carrying off immense booty to their homes south of the Danube. The _Persians_ conquered _Armenia_, took _Valerian_ prisoner, advanced into Syria, and burned Antioch. TO DIOCLETIAN (A.D. 284).--It would seem as if the Roman empire was on the verge of dissolution. But a series of vigorous emperors--among them _Claudius_ (268-270) and _Aurelian_ (270-275)--quelled rebellion within its borders, and re-established its boundaries; although _Aurelian_ gave up to the Goths _Dacia_, which had been of no benefit to the empire. _Probus_ (276-282) was a prudent as well as valiant ruler. _Carus_ (282-283) invaded Persia, captured _Seleucia_ and _Ctesiphon_, and might, perhaps, have completed the conquest of the country, but for his death. _Numerianus_ (283-284) was the last in the succession of rulers during this period of military control, of which the corruption of the army was the worst result. II. THE ABSOLUTE MONARCHY (TO A.D. 375).