Many details in the administration of the law, and particularly of the criminal law, were improved. To cure corruption in the Senate the ballot was introduced at elections to magistracies. The finances of the state were economically managed, and taxpayers were most carefully guarded from oppression. Trajan never lacked money to expend on great works of public utility; as a builder, he may fairly be compared with Augustus. His forum and its numerous appendages were constructed on a magnificent scale. Many regions of Italy and the provinces, besides the city itself, benefited by the care and munificence which the emperor bestowed on such public improvements. His attitude toward religion was, like that of Augustus, moderate and conservative. The famous letter to Pliny about the Christians is, according to Roman ideas, merciful and considerate. It was impossible, however, for a Roman magistrate of the time to rid himself of the idea that all forms of religion must do homage to the civil power. Hence the conflict which made Trajan appear in the eyes of Christians like Tertullian, the most infamous of monsters. On the whole, Trajan's civil administration was sound, careful, and sensible, rather than brilliant or epoch-making.
[Illustration: Rome under Trajan--A chariot race.]
In 113 or 114 Trajan left Italy to make war in the East. The never-ending Parthian problem confronted him, and with it were more or less connected a number of minor difficulties. Already by 106 the position of Rome in the East had been materially improved by the peaceful annexation of districts bordering on the province of Syria. The district of Damascus, hitherto a dependency, and the last remaining fragment of the Jewish kingdom, were incorporated with Syria; Bostra and Petra were permanently occupied, and a great portion of the Nabathæan kingdom was constituted the Roman province of Arabia. Rome thus obtained mastery of the most important positions lying on the great trade-routes from East to West. These changes could not but affect the relations of the Roman with the Parthian empire, and the affairs of Armenia became, in 114, the occasion of war. Trajan's campaigns in the East ended in complete though brilliant failure. In the retreat from Ctesiphon (117), the old emperor tasted for almost the first time the bitterness of defeat in the field. He attacked the desert city of Hatra, westward of the Tigris, whose importance is still attested by grand ruins. The want of water made it impossible to maintain a large force near the city, and the brave Arabs routed the Roman cavalry. Trajan, who narrowly escaped being killed, was forced to withdraw.