Philippus was born in about AD 204 in a small town in the region of Trachonitis in south-western Syria as the son of an Arab chieftain called Marinus, who held Roman equestrian rank.
He was to become known as 'Philip the Arab', the first man of that race to hold the imperial throne.
He was the deputy of the praetorian prefect Timesitheus at the time of the Mesopotamian campaigns under the reign of Gordian III.
His treacherousness paid off, for the troops not only hailed him emperor of the Roman empire but on the same day also killed Gordian III in order to make way for him (25 February AD 244).
Philippus, eager not to be understood as the murder of his predecessor, had a report sent to the senate, claiming that Gordian III had died of natural causes, and even prompted his deification.
Back in Rome, his father-in-law (or brother-in-law) Severianus was granted the governorship of Moesia.
To further increase his grip on power he was also sought to establish a dynasty. His five or six year old son Philippus was declared Caesar (junior emperor) and his wife, Otacilia Severa, was declared Austusta. In a more strained attempt to increase his legitimacy Philip even deified his late father Marinus. Also his insignificant home town in Syria was now elevated to the status of a Roman colony and dubbed 'Philippopolis' (City of Philip).
Some rumours have it, that Philippus was the first Christian emperor. This though appears untrue and is most likely based on the fact that he was very tolerant toward the Christians.
Philip is also known to have clamped down on abuses in the treasury administration. He felt a deep dislike for homosexuality and castration and issued laws against them. He maintained public works and improved some of the water supply to the western part of Rome. But he could do little to ease the burden of extortionate taxes to pay for the large armies the empire required for its protection.
Philippus was not yet long in office when news arrived that the Dacian Carpi had crossed the Danube. Neither Severianus, nor the generals stationed in Moesia were able to make any significant impact on the barbarians.
His standing on his return to Rome was much increased and Philippus used this in July or August AD 247 to promote his son to the position of Augustus and pontifex maximus. Furthermore in AD 248 the two Philips held both consulships and the elaborate celebration of the 'thousandth birthday of Rome' was held.
Should all this have put Philippus and his son on a sure footing, in the very same year three separate military commanders rebelled and assumed the throne in various provinces. First there was the emergence of a certain Silbannacus on the Rhine. His challenge to the established ruler was a brief one and he vanished from history as quickly as he emerged. A similarly brief challenge was that of a certain Sponsianus on the Danube.
But in early summer of the year AD 248 more serious news reached Rome. Some of the legions on the Danube had hailed an officer called Tiberius Claudius Marinus Pacatianus emperor. This apparent quarrelling among the Romans in turn only further incited the Goths who were not being paid their tribute promised by Gordian III. So the barbarians now crossed the Danube wreaking havoc in northern parts of the empire.
Almost simultaneously a revolt erupted in the east. Philippus' brother Gaius Julius Priscus, in his new position as 'praetorian prefect and ruler of the east', was acting as an oppressive tyrant. In turn the eastern troops appointed a certain Iotapianus emperor.
On hearing this grave news, Philippus began to panic, convinced the empire was falling apart. In a unique move, he addressed the senate offering to resign.
But the situation on the Danube still remained critical. Severianus was struggling to regain control. Many of his soldiers were deserting to the Goths. And so to replace Severianus, the steadfast Decius was now sent to govern Moesia and Pannonia. His appointment brought almost immediate success.
In a bizarre turn of events the Danubian troops, so impressed by their leader, proclaimed Decius emperor in AD 249. Decius protested he had no desire to be emperor, but Philippus gathered troops and moved north to destroy him.