How did Augustin ever believe in the goodwill and good faith of this adventurer full of coarse passions, so far as to put his final hopes in him? Augustin knew men very well; he could detect low and hypocritical natures at a distance. How came it that he was taken in by Boniface?
Well, Augustin wanted his support, first of all, when he came as Imperial Commissioner to Carthage to bring the Donatists into line. Generally, we see only the good points of people who do us good turns. Besides, in order to propitiate the bishop, and the devout Court at Ravenna, the Tribune advertised his great zeal in favour of Catholicism. His first wife, a very pious woman whom he seems to have loved much, encouraged him in this. When she died, he was so overcome by despair that he took refuge in the extremest practices of religion—and in this, perhaps, he was quite sincere. It is also possible that he was becoming discredited at Ravenna, where they must have known about his oppressions and suspected his ambitious intrigues. Anyhow, whether he was really disgusted with the world, or whether he deemed it prudent to throw a little oblivion over himself just then, he spoke on all hands of resigning his post and living in retreat like a monk. It was just at this moment that Augustin and Alypius begged him not to desert the African army.
They met the Commander-in-Chief at Thubunæ, in Southern Numidia, where, no doubt, he was reducing the Nomads. We must remark once more Augustin's energy in travelling, to the very eve of his death. It was a long and dangerous road from Hippo to Thubunæ. Before making up his mind to so much fatigue, the old bishop must have judged the situation to be very serious. At Thubunæ, was Boniface playing a game, or was he, indeed, so crushed by his grief that the world had become unbearable and he pondered genuine thoughts of changing his way of life? What is sure is, that he gave the two prelates the most edifying talk. When they heard the Count of Africa speaking with unction of the cloister and of his desire to retire there, they were a little astonished at so much piety in a soldier. Besides, these excellent resolutions were most inconvenient for their plans. They remonstrated with him that it was quite possible to save one's soul in the army, and quoted the example of David, the warrior king. They ended by telling him all the expectations they founded upon his resource and firmness. They begged him to protect the churches and convents against fresh attacks of the Donatists, and especially against the Barbarians of Africa. These were at this moment breaking down all the old defence lines and laying waste the territories of the Empire.
Boniface allowed himself to be easily convinced—promised whatever he was asked. But he never budged. From now on, his conduct becomes most singular. He is in command of all the military strength of the province, and he takes no steps to suppress the African looters. It would seem as if he only thought of filling the coffers of himself and his friends. The country was so systematically scoured by them that, as Augustin said, there was nothing more left to take.
This inactivity lent colour to the rumours of treason. Nor is it impossible that he had cherished a plan from the beginning of his command to cut out an independent principality for himself in Africa. Was this the reason that he dealt softly with the native tribes, so as to make certain of their help in case of a conflict with the Imperial army? However that may be, his behaviour was not frank. Some years later, he landed on the Spanish coast to war against the Vandals under the command of the Prefect Castinus, and there he married a Barbarian princess who was by religion an Arian. It is true that the new Countess of Africa became a convert to Catholicism. But her first child was baptized by Arian priests, who rebaptized, at the same time, the Catholic slaves of Boniface's household. This marriage with a Vandal, these concessions to Arianism, gave immense scandal to the orthodox. Rumours of treason began to float about again.
No doubt Boniface took great advantage of his fidelity to the Empress Placidia. But he was standing between the all-powerful Barbarians and the undermined Empire. He wanted to remain on good terms with both, and then, when the hour came, to go over to the stronger. This double-faced diplomacy caused his downfall. His rival Aëtius accused him of high treason before Placidia. The Court of Ravenna declared him an enemy of the Empire, and an army was sent against him. Boniface did not hesitate; he went into open rebellion against Rome.
Augustin was thunderstruck by his desertion. But what way was there to make this violent man listen to reason, who had at least the appearances of right on his side, since there was a chance they had slandered him to the Empress, and who thought it quite natural to take vengeance on his enemies? His recent successes had still more intoxicated him. He had just defeated the two generals who had been sent to reduce him, and he was accordingly master of the situation in Africa. What was he going to do? The worst resolutions were to be feared from this conqueror, all smarting, and hungry for revenge…. Nevertheless, Augustin resolved to write to him. His letter is a masterpiece of tact, of prudence, and also of Christian and episcopal firmness.
It would have been dangerous to declare to this triumphant rebel: "You are in the wrong. Your duty is to submit to the Emperor, your master." Boniface was quite capable of answering: "What are you interfering for? Politics are no business of yours. Look after your Church!" This is why Augustin very cleverly speaks to him from beginning to end of his letter simply as a bishop, eager for the salvation of a very dear son in Jesus Christ. And so, by keeping strictly to his office of spiritual director, he gained his end more surely and entirely; and, as a doctor of souls, he ventured to remind Boniface of certain truths which he would never have dared to mention as counsellor.
According to Augustin, the disgrace of the Count, and the evils which this event had brought on Africa, came principally from his attachment to worldly benefits. It was the ambition and covetousness of himself and his followers which had done all the harm. Let him free himself from perishable things, let him prevent the thefts and plundering of those under him. Let him, who some time ago wished to live in perfect celibacy, now keep at least to his wife and no other. Finally, let him remember his sworn allegiance. Augustin did not mean to go into the quarrel between Boniface and Placidia, and he gave no opinion as to the grievances of either. He confined himself to saying to the general in rebellion: "If you have received so many benefits from the Roman Empire, do not render evil for good. If, on the other hand, you have received evil, do not render evil for evil."
It is clear that the Bishop of Hippo could scarcely have given any other advice to the Count of Africa. To play the part of political counsellor in the very entangled state of affairs was extremely risky. How was it possible to exhort a victorious general to lay down his arms before the conquered? And yet, in estimating the situation from the Christian standpoint alone, Augustin had found a way to say everything essential, all that could profitably be said at the moment.