The splendour of these games had dazzled Rome and Italy, and restored to Pompey a great part of his prestige; but the levies of troops, which he was obliged to order soon afterwards, caused great discontent. Several tribunes vainly opposed their veto; they were obliged to renounce a struggle which had Pompey, and especially Crassus, to sustain it. [Sidenote: Departure of Crassus for Syria.] VII. Without waiting for the end of his consulship, Crassus determined on quitting Rome; he left in the last days of October.[677] As we have said, it was not the government of Syria which excited his ardour; his aim was to carry the war into the country of the Parthians, in order to acquire new glory, and obtain possession of the treasures of those rich countries. The idea of this expedition was not new. The Parthians had long awakened the jealousy of Rome. They had extended their frontiers from the Caucasus to the Euphrates,[678] and considerably increased their importance; their chief assumed, like Agamemnon, the title of _king of kings_. It is true that the part of Mesopotamia taken from the Parthians by Tigranes had been restored to them by Lucullus, and Pompey had renewed the treaty which made the Euphrates the frontier of the empire of the Arsacides. But this treaty had not always been respected, for it was not one of the habits of the Republic to suffer a too powerful neighbour. Nevertheless, different circumstances might, at this moment, lead the Senate to make war upon the Parthians. While A. Gabinius exercised the command in Syria, Mithridates, dethroned, on account of his cruelty, by his younger brother Orodes, had invoked the support of the proconsul; and the latter was on the point of giving it, when Pompey sent him orders to repair first into Egypt to replace Ptolemy on his throne. Mithridates, besieged in Babylon, had surrendered to his brother, who had caused him to be put to death.[679] On another hand, the Parthians were always at war with the kings of Armenia, allies of the Romans. The Senate, had it the wish, was not, therefore, in want of pretexts for declaring war. It had to avenge the death of a friendly pretender, and to sustain a threatened ally. To what point could the law of nations be invoked? That is doubtful; but, for several centuries, the Republic had been in the habit of consulting its own interests much more than justice, and the war against the Parthians was quite as legitimate as the wars against Perseus, Antiochus, or Carthage. Nevertheless, this enterprise encountered a warm opposition at Rome; the party hostile to the consuls feared the glory which it might reflect upon Crassus, and many prudent minds dreaded the perils of so distant an expedition; but Cæsar, who had inherited that passion of the ancient Romans who dreamt for their town the empire of the world, encouraged Crassus in his projects, and, in the winter of 700, he sent Publius to his father, with 1,000 picked Gaulish cavalry.