The Roman Age of Chaos began in 235 CE, when the Emperor Alexander Severus was set upon by his own troops, who replaced him with Maximinus I—Max Thrax, as he is sometimes known. By the time Gordian III assumed the throne in 238, at the ripe old age of 13, there had already been five rulers after Alexander Severus. The youthful, good-natured Gordian managed to survive for six years, among the longest reigns of any emperor during the Crisis, before being killed. His successor Philip I attempted to solidify his position by naming his son Philip II as co-Caesar, but their reign lasted just five years. Trajan Decius, who defeated the two Philips in 249, was dead two years later. Trebonianus Gallus attempted to restore peace to the Empire, ending the wars with the Goths, but he too was killed by his own men after just two years on the throne. The Age of Chaos did not end until Diocletian assumed command in 284, ushering in the Tetrarchy and closing the book on five decades of near-anarchy.