Gallus (Caius Vibius Trebonianus Gallus)gălˈəs, d. 253 or 254, Roman emperor after 251. He fought in the eastern campaign that proved fatal to Decius. Gallus became emperor and accepted Hostilianus, Decius' son, as his colleague, or nominal coruler. In Gallus' reign the Persians overran Mesopotamia, and the Goths invaded Moesia and Thrace. In 252 or 253 a new invasion was repelled in the Danube valley by the general Aemilianus, whose troops proclaimed him emperor. Gallus sent Valerian to put down the sedition. Aemilianus entered Italy, and the army murdered Gallus. Aemilianus succeeded, and Valerian succeeded him soon afterward.
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