Military campaigns of Julius Caesar
The military campaigns of Julius Caesar constituted both the Gallic War (58 BC-51 BC) and Caesar's civil war (50 BC-45BC) in 59 BC, which had been highly controversial. The Gallic War mainly took place in what is now France. In 55 and 54 BC, he invaded Britain, although he made little headway. The Gallic War ended with complete Roman victory at the Battle of Alesia. This was followed by the civil war, during which time Caesar chased his rivals to Greece, decisively defeating them there. He then went to Egypt, where he defeated the Egyptian pharaoh and put Cleopatra on the throne. He then finished off his Roman opponents in Africa and Hispania. Once his campaigns were over, he served as Roman dictator until his assassination root on March 15, 44 BC. These wars were critically important in the transition of the Roman Republic into the Roman Empire.
Western Roman Empire
With the assassination of the Emperor Alexander Severus on 18 March 235, the Roman Empire sank into a 50-year period of civil war, now known as the Crisis of the Third Century. The rise of the bellicose Sasanian Empire in place of Parthia posed a major threat to Rome in the east, as demonstrated by Shapur I's capture of Emperor Valerian in 259. Valerian's eldest son and heir-apparent, Gallienus, succeeded him and took up the fight on the eastern frontier. Gallienus' son, Saloninus, and the Praetorian Prefect Silvanus were residing in Colonia Agrippina (modern Cologne) to solidify the loyalty of the local legions. Nevertheless, Marcus Cassianius Latinius Postumus – the local governor of the German provincesrebelled; his assault on Colonia Agrippina resulted in the deaths of Saloninus and the prefect. In the confusion that followed, an independent state known in modern historiography as the Gallic Empire emerged.