Origen to tutor Alexander in Christianity. While Alexander was being educated in the Christian doctrines, the northern portion of his empire was being invaded by Germanic and Sarmatian tribes. A new and menacing enemy started to emerge directly after Alexander's success in the Persian war. In 234, the barbarians crossed the Rhine and Danube in hordes that caused alarm as far as Rome. The soldiers serving under Alexander, already demoralized after their costly war against the Persians, were further discontented with their emperor when their homes were destroyed by the barbarian invaders. As word of the invasion spread, the emperor took the front line and went to battle against the Germanic invaders. The Romans prepared heavily for the war, building a fleet to carry the entire army across. However, at this point in Alexander's career, he still knew little about being a general. Because of this, he hoped the mere threat of his armies would be sufficient to persuade the hostile tribes to surrender. Severus enforced a strict military discipline in his men that sparked a rebellion among his legions. Due to incurring heavy losses against the Persians, and on the advice of his mother, Alexander attempted to buy the Germanic tribes off, so as to gain time. It was this decision that resulted in the legionaries looking down upon Alexander. They considered him dishonorable and feared he was unfit to be Emperor. Under these circumstances the army swiftly looked to replace Alexander. Gaius Julius Verus Maximinus was the next best option. He was a soldier from Thrace who had a golden reputation and was working hard to increase his military status. He was also a man with superior personal strength, who rose to his present position from a peasant background. With the Thracian's hailing came the end of the Severan Dynasty, and, with the growing animosity of Severus' army towards him, the path for his assassination was paved. Assassination Alexander was forced to face his German enemies in the early months of 235. By the time he and his mother arrived, the situation had settled, and so his mother convinced him that to avoid violence, trying to bribe the German army to surrender was the more sensible course of action. According to historians, it was this tactic combined with insubordination from his own men that destroyed his reputation and popularity. Alexander was thus assassinated together with his mother on