In 384, Martin of Tours had a meeting with the usurper-emperor Magnus Maximus, who was humiliated. It was an important event, marking the Church's ambition to gain control of the imperial court.
The fourth-century author Sulpicius Severus is the author of the Life of Saint Martin, in which he describes the life of the famous Christian leader, who introduced monastic life in Gaul. In 384, Martin had a meeting with the usurper-emperor Magnus Maximus, who was humiliated. The story is offered below in the translation by Peter Schaff.
Two years later, Ambrose of Milan acted in a similar fashion towards the emperor Valentinian II, and later (in 390) towards Theodosius I. After these three incidents in seven years, there could be no misunderstanding about how the Church wanted emperors to behave.
 When a number of bishops from various parts had assembled to the Emperor Maximus, a man of fierce character, and at that time elated with the victory he had won in the civil wars, and when the disgraceful flattery of all around the emperor was generally remarked, while the priestly dignity had, with degenerate submissiveness, taken a second place to the royal retinue, in Martin alone, apostolic authority continued to assert itself.
For even if he had to make suit to the sovereign for some things, he commanded rather than entreated him; and although often invited, he kept away from his entertainments, saying that he could not take a place at the table of one who, out of two emperors, had deprived one of his kingdom, and the other of his life.
At last, when Maximus maintained that he had not of his own accord assumed the sovereignty, but that he had simply defended by arms the necessary requirements of the empire, regard to which had been imposed upon him by the soldiers, according to the Divine appointment, and that the favor of God did not seem wanting to him who, by an event seemingly so incredible, had secured the victory, adding to that the statement that none of his adversaries had been slain except in the open field of battle, at length, Martin, overcome either by his reasoning or his entreaties, came to the royal banquet.
The king was wonderfully pleased because he had gained this point. Moreover, there were guests present who had been invited as if to a festival; men of the highest and most illustrious rank, - the prefect, who was also consul, named Evodius, one of the most righteous men that ever lived; two courtiers possessed of the greatest power, the brother and uncle of the king, while between these two, the presbyter of Martin had taken his place; but he himself occupied a seat which was set quite close to the king.
About the middle of the banquet, according to custom, one of the servants presented a goblet to the king. He orders it rather to be given to the very holy bishop, expecting and hoping that he should then receive the cup from his right hand. But Martin, when he had drunk, handed the goblet to his own presbyter, as thinking no one worthier to drink next to himself, and holding that it would not be right for him to prefer either the king himself, or those who were next the king, to the presbyter.
And the emperor, as well as all those who were then present, admired this conduct so much, that this very thing, by which they had been undervalued, gave them pleasure. The report then ran through the whole palace that Martin had done, at the king’s dinner, what no bishop had dared to do at the banquets of the lowest judges.
And Martin predicted to the same Maximus long before, that if he went into Italy to which he then desired to go, waging war, against the Emperor Valentinianus, it would come to pass that he should know he would indeed be victorious in the first attack, but would perish a short time afterwards. And we have seen that this did in fact take place. For, on his first arrival Valentinian had to betake himself to flight but recovering his strength about a year afterwards, Maximus was taken and slain by him within the walls of Aquileia.