Age 13, Gordian became the youngest sole emperor to rule the united ancient Roman Empire.

238 AD, the crisis of the 3rd century. A new emperor had to be chosen, the senators elected 2 of their own number: Balbinus and Pupienus, with equal status and power. Both were old aristocrats, as the Senate could not agree on a single strong candidate. 

on the day of their accession, these 2 newly proclaimed emperors were compelled by the Roman mob to accept as their colleague Gordian, whose grandfather had been emperor before him. He was merely a 13 yo puppet. The old emperors did their best, but they were unpopular with too many people, including their own soldiers. They were degraded, humiliate, murdered by praetorians.

The Sassanian Persians saw Rome as an easy target: severely short of money, wracked by civil wars, with a teenager on the throne. They became predatory and seized the opportunity to attack Rome's eastern border. There was unrest on other borders too, but the main enemy was Persia. The praetorian prefect prepared the planned expedition against Persia meticulously. 

He was clearly more concerned with his military duties than with seizing Powder, which he already had. In late 242 AD, Emperor Gordian reached Antioch with his full-court and a massive army. He would never return. Gordian was 19 when he died, and his death remains a mystery. He may have died in battle, but more likely he was killed by his own men after the campaign.