AR Denarius, AD 196-198, Rome, 17.4mm, 2.34g, 0°, RIC IVi 11.
Obv: M AVR ANTON CAES PONTIF. Bare head, draped bust right.
Rev: MARTI VLTORI. Mars advancing right with spear and trophy.
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Marcus Aurelius Antoninus, born Lucius Septimius Bassianus, and commonly known as Caracalla, was Roman emperor from 209 to 217. The eldest son of Septimius Severus, he ruled jointly with his younger brother Geta until he murdered the latter in 211. Caracalla is remembered as one of the most notorious emperors because of the massacres and persecutions he authorized throughout the empire.

According to Aurelius Victor in his Epitome de Caesaribus, the agnomen "Caracalla" refers to a Gallic cloak that Caracalla adopted as a personal fashion, which spread to his army and his court. Cassius Dio and the Historia Augusta agree that his nickname was derived from his cloak, but does not mention its country of origin.

Caracalla's reign was also notable for the Constitutio Antoniniana, granting Roman citizenship to all freemen throughout the Roman Empire, according to historian Cassius Dio in order to increase taxation. He then had the silver content in Roman coinage reduced by 25 percent in order to increase the pay of the legions. He also ordered the construction of a large thermae outside Rome, the remains of which, known as the Baths of Caracalla, can still be seen today.

While traveling from Edessa to continue the war with Parthia, Caracalla was assassinated while
urinating at a roadside near Carrhae on April 8, AD 217, by Julius Martialis, an officer of his personal bodyguard. Herodian says that Martialis' brother had been executed a few days earlier by Caracalla on an unproven charge; Cassius Dio, on the other hand, says that Martialis was resentful at not being promoted to the rank of centurion. The escort of the emperor gave him privacy to relieve himself, and Martialis then ran forward and killed Caracalla with a single sword stroke. He immediately fled on horseback, but was in turn killed by a bodyguard archer. Caracalla was succeeded by the Praetorian Guard Prefect Macrinus.