ALEXANDER SEVERUS was only in his thirteenth year when he became emperor, in 222. His mother played a major part in his administration, and he appears to have been a virtuous leader. During the late 220s, the eastern frontiers of the Empire came under threat from the Persians. In the early 230s, Alexander led a campaign which, although it was declared a victory, produced no real gains. It seems that troops had been withdrawn from the Rhine and Danube to fight against the Persians. Taking advantage of the situation, Germanic invaders had crossed the rivers. A counter offensive was undertaken; a bridge of boats (commemorated on a coin of 235) being built across the Rhine. Apparently, however, Alexander preferred to buy peace rather than fight. This angered the soldiery, who mutinied; killing Alexander and his mother near Moguntiacum (Mainz), in Upper Germany.