Caius Pius Esuvius Tetricus was Emperor of the Gallic Empire (Imperium Galliarum) from 270/271 to 273 AD, following the murder of Victorinus. Tetricus, who ruled with his son, Tetricus II, was the last of the Gallic emperors. Tetricus was born to a noble family and held the administrative rank of praeses provinciae (provincial governor) of Aquitania at the time of Victorinus' death. Victorinus' mother, Victoria, paid the army heavily to declare Tetricus emperor near Burdigalia (Bordeaux, France), which was approved in Gaul and Britain. Following his appointment, Tetricus repelled Germanic tribes that took advantage of the confusion following the death of Victorinus to invade. Tetricus installed his capital at Augusta Treverorum (present Trier, Germany, near the vital Rhine border, hence later seat of a Tetrarch) and appointed his son, Tetricus II, Caesar.

Main Roman Coin Book and Other References:

RIC = Mattingly, Harold    The Roman Imperial Coinage
BMC = Coins of the Roman Empire in the British Museum
RSC = Seaby, H A    Roman Silver Coinage
RCV = Sear, David R    Roman Coins and Their Values
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WW = Wildwinds.com (reference & attribution site)