The apparent tranquillity of Gaul, and the imminent danger of the eastern provinces, offered a specious pretence for the design which was artfully concerted by the imperial ministers. They resolved to disarm the cæsar; to recall those faithful troops who guarded his person and dignity; and to employ, in a distant war against the Persian monarch, the hardy veterans who had vanquished, on the banks of the Rhine, the fiercest nations of Germany. While Julian used the laborious hours of his winter quarters at Paris in the administration of power, which, in his hands, was the exercise of virtue, he was surprised by the hasty arrival of a tribune and a notary, with positive orders from the emperor which they were directed to execute, and he was commanded not to oppose. Constantius signified his pleasure, that four entire legions, the Celtæ and Petulants, the Heruli, and the Batavians, should be separated from the standard of Julian, under which they had acquired their fame and discipline; that in each of the remaining bands three hundred of the bravest youths should be selected; and that this numerous detachment, the strength of the Gallic army, should instantly begin their march, and exert their utmost diligence to arrive, before the opening of the campaign, on the frontiers of Persia. The cæsar foresaw and lamented the consequences of this fatal mandate. Most of the auxiliaries, who engaged their voluntary service, had stipulated that they should never be obliged to pass the Alps. The public faith of Rome and the personal honour of Julian had been pledged for the observance of this condition. Such an act of treachery and oppression would destroy the confidence and excite the resentment of the independent warriors of Germany, who considered truth as the noblest of their virtues, and freedom as the most valuable of their possessions. The legionaries, who enjoyed the titles and privileges of Romans, were enlisted for the general defence of the republic; but those mercenary troops heard with cold indifference the antiquated names of the republic and of Rome. Attached, either from birth or long habit, to the climate and manners of Gaul, they loved and admired Julian; they despised, and perhaps hated, the emperor; they dreaded the laborious march, the Persian arrows, and the burning deserts of Asia. They claimed as their own the country which they had saved; and excused their want of spirit, by pleading the sacred and more immediate duty of protecting their families and friends.
The apprehensions of the Gauls were derived from the knowledge of the inevitable danger. As soon as the provinces were exhausted of their military strength, the Germans would violate a treaty which had been imposed on their fears; and, notwithstanding the abilities and valour of Julian, the general of a nominal army, to whom the public calamities would be imputed, must find himself, after a vain resistance, either a prisoner in the camp of the barbarians, or a criminal in the palace of Constantius. If Julian complied with the orders which he had received, he would subscribe to his own destruction, and that of a people who deserved his affection. But a positive refusal was an act of rebellion, and a declaration of war. The inexorable jealousy of the emperor, the peremptory, and perhaps insidious, nature of his commands, left not any room for a fair apology or candid interpretation; and the dependent station of the cæsar scarcely allowed him to pause or to deliberate. Solitude increased the perplexity of Julian; he could no longer apply to the faithful counsels of Sallust, who had been removed from his office by the judicious malice of the eunuchs. Unable to resist, unwilling to comply, Julian expressed, in the most serious terms, his wish, and even his intention of resigning the purple, which he could not preserve with honour, but which he could not abdicate with safety.