Caracalla became Roman emperor, together with his brother Geta in 211, after the death of his father Septimius Severus. The campaign against the Maeatae in Britain was immediately abandoned. Caracalla killed his brother the same year, because they couldn't agree on a lot of things.
In 213, he waged war versus the Allemanni, who had settled the north of the Agri Decumates. The Allemanni were defeated but remained hostile, thereby ensuring the loss of the territory for the Roman Empire.
In 214, Caracalla annexed the Roman vassal state Osroene.
Roman Dacia suffered from invasions of the Carpi and the free Dacians.
In 216, Caracalla started a war with king Artabanus IV of the Parthian Empire, sacking the city of Arbela. He also tried to turn Armenia into a Roman province and deposed king Khosrov. Armenia and Osroene revolted against the Romans. While subduing Osroene, the Parthians invaded Roman Mesopotamia. Caracalla was killed near Carrhae by an officer of his bodyguard in 217.