Philip's rise to prominence began through the intervention of his brother Priscus, who was an important official under the emperor Gordian III. His big break came in 243, during Gordian III's campaign against Shapur I of Persia, when the Praetorian prefect Timesitheus died under unclear circumstances. At the suggestion of his brother Priscus, Philip became the new Praetorian prefect, with the intention that the two brothers would control the young Emperor and rule the Roman world as unofficial regents. Following a military defeat, Gordian III died in February 244 under circumstances that are still debated. While some claim that Philip conspired in his murder, other accounts (including one coming from the Persian point of view) state that Gordian died in battle. Whatever the case, Philip assumed the purple robe following Gordian's death. According to Edward Gibbon: