Caracalla, Marcus Aurelius Antonius(Reign: 211-217 AD) Born in 186, he was the son of Septimius Severus and Julia Domna. His name was derived from the Celtic name of his hooded tunic. Caracalla accompanied his father in many of his travels. After Severus' death in 211, Caracalla and his brother Geta ruled as co-emperors. A year later Caracalla killed Geta and many of his supporters, including his own wife. On July 212 he decreed the "Constitutio Antoniniana", which awarded Roman citizenship to almost all the inhabitants of the Empire, and by that extended to them the inheritance tax paid by Roman citizens. From 213 on, he conducted wars in Germany, around the Danube and in the East. While planning the conquest of Parthia he was assassinated by Macrinus in 217 AD.