Hastings' Dictionary of the New Testament 
Trajan’s reign is of interest to the student of early Church history on account of its connexion with the treatment of Christians by the State. Spain, which had contributed during the 1st cent. a long line of celebrated names to Roman literature,-the Elder Seneca, Seneca the philosopher, Columella the agriculturist, Pomponius Mela the geographer, Lucan the epic poet, Martial the epigrammatist, and Quintilian the rhetorician,-gave in Trajan its first Emperor to the Roman Empire.
M. Ulpius Traianus was born at Italica, in the province of Hispania Baetica, which corresponded territorially to the modern Andalucia, on Sept. 18, a.d. 52 or 53. His father was the first of the family to attain to senatorial rank. Young Trajan served as military tribune under his father, who was governor of the important province Syria, in the year 76. This was only part of an extremely extensive military experience which fell to the lot of the future Emperor in his early manhood. It may be doubted, in fact, if any other aristocrat of the day had spent as much time in the field. Fortified by an assured military reputation, he returned to Rome in 78, and then passed through the regular succession of offices, attaining the praetorship, probably in 85. From 89 to 97 he was in command of a legion serving successively in Spain and Germany, and in the latter country he quelled a revolt of two legions at Vindonissa (modern Windisch). In recognition of these services, he was made one of the two chief consuls for 91. After a period of inaction he was, at the election of Nerva as Emperor in 96, appointed governor of the mountainous part of Germany ( provincia Germania Superior ), to secure a new frontier to the Empire, taking in the Agri Decumates (modern Schwarzwald, Black Forest). The aged Nerva on 27th October 97 adopted him as his son and successor, and he thus took the name Imperator Caesar Nerva Traianus Augustus. In the same year he obtained the honorary title ‘Germanicus’ for his military exploits against the Germans. Later titles conferred upon him may be here enumerated: ‘Pater Patriae’ in 98, ‘Dacicus’ at the end of 102, ‘Optimus’ in 114, and ‘Parthicus’ in 116. Nerva died on 25th January 98, and Trajan thus succeeded to the sole rule of the Empire, but he did not leave Germany till about a year after his accession. In 99 he reached Rome. He had already proved himself the ablest general of the time. He now showed affability to all classes, and conducted all his relations with the Senate and aristocracy in the most tactful manner. Details of his rule need not be given, but those best qualified to judge consider that of all the Roman Emperors, with the possible exception of Augustus, Trajan was the wisest, most competent, and greatest. Much of his reign was spent in necessary military operations, but the conduct of civil affairs was quite as excellent. The Emperor had to leave Rome in March 101 for the invasion of Dacia, which had proved a very troublesome foe in the time of Domitian. After two campaigns the Decebalus was defeated and his capital Sarmizegetusa captured (end of 102). A permanent bridge over the Danube, still in use, was built at Drobetae. A rising of the Decebalus, however, took place late in 104, and early in 105 Dacia was again invaded by the Romans. Baffled and defeated, the Decebalus committed suicide. The Dacian population was almost completely exterminated, and a new province Dacia was created, to which colonists were introduced from various parts of the Empire. These were the ancestors of the present inhabitants of Transylvania and Rumania, and their origin explains the character of the Rumanian language and the sympathies of the Rumanian people to-day. By the end of 106 Trajan was again in Rome. In the preceding year it had been necessary, in the interests of trade, to annex the territory of the turbulent Nabataean tribes of Arabia Petraea, and thus the Roman province Arabia was formed. From 106 to about 112 Trajan was in Italy, and among much beneficial legislation the permanent establishment of the system of alimentationes , inaugurated by Nerva, deserves mention. This was a system for the support of poor boys and girls, including orphans and foundlings, throughout Italy. Trajan’s Forum and its features have been referred to in the article Rome. His interest in provincial government comes out in the official correspondence with C. Plinius Caecilius Secundus, governor of the province Bithynia-Pontus about 111-113. The reader is impressed by ‘the careful attention paid to details … the consistent desire … to respect local customs and usages, the avoidance of general rules and principles, and the equitable spirit which insists on the execution of the laws, but observes vested interests, and avoids the appearance of anything arbitrary’ (E. G. Hardy, C. Plinii Caecilii Secundi Epistulae ad Traianum Imperatorem cum eiusdem Responsis , p. 12). Pliny, having written that he had never taken part in trials of Christians, asked the Emperor what procedure he ought to follow. Trajan laid down that they must not be sought out, but that if duly prosecuted and convicted they must pay the penalty of execution. There is no real reason to suppose that Trajan inaugurated this policy. It was probably in the time of Vespasian or one of the other Flavian Emperors that the confession of Christianity in itself began to be regarded as an offence against the State, punishable with death. The affairs of Armenia caused the inevitable conflict with the Parthians on the eastern frontier, which occupied the last years of Trajan’s life. The Emperor himself set out for the East at the end of 113, and in a succession of campaigns he was able to subdue the enemies of Rome and to add three provinces to the Empire-Armenia minor, Mesopotamia, and Assyria. But the conquest had been too rapid, and the last had to be relinquished. Trajan died at Selinus in Cilicia in August, 117.
Literature.-The chief ancient authorities are Xiphilinus’ Epitome of Dio Cassius , bk. lxviii.; Pliny, Panegyricus and Correspondence with Trajan . There are also many important inscriptions and coins. Besides the relevant parts of the histories of H. Schiller, Geschichte der römischen Kaiserzeit , i. [Gotha, 1883]; V. Duruy, History of Rome , Eng. translation, 6 vols., London, 1883-86; J. B. Bury, Student’s History of the Roman Empire , do., 1893; A. von Domaszewski, Geschichte der römischen Kaiser , ii. [Leipzig, 1909] 171-185, there are the special monographs: J. Dierauer, Beiträge zu einer kritischen Geschichte Trajans , Leipzig, 1868; G. A. T. Davles, Lecturer in Roman History in the University of Aberdeen, is preparing a monograph on the Dacian campaigns (cf. his paper ‘The Dacian Campaign of Trajan in a.d. 102,’ read before the Society for the Promotion of Roman Studies on 3rd March 1914, and to be published in Jrs [Note: Rs Journal of Roman Studies.]); E. G. Hardy’s C. Plinii Caecilii Secundi Epistulae ad Traianum Imperatorem cum eiusdem Responsis , London, 1889, is important. On Trajan’s attitude to the Christians, consult W. M. Ramsay, The Church in the Roman Empire before a.d. 170 , do., 1893, ch. x. pp. 196-225, and E. G. Hardy, Studies in Roman History , do., 1906, ch. vi. pp. 78-95; K. J. Neumann, Der römische Staat und die allgemeine Kirche bis auf Diocletian , I. [Leipzig, 1890] 17-26, may also be read.