On the other hand the army had been one of the most influential agents in the spread of the material and cultural aspects of Roman civilization. The great highways of the empire, bridges, fortifications and numerous public works of other sorts were constructed by the soldiers. Every camp was a center for the spread of the Latin language and Roman institutions and the number of Roman citizens was being augmented continuously by the stream of discharged auxiliaries whose term of service had expired. In the _canabae_, or villages of the civilian hangers-on of the army corps, sprang up organized communities of Roman veterans with all the institutions and material advantages of municipal life. The constant movement of troops from one quarter of the empire to another furnished a ready medium for the exchange of cultural, in particular of religious, ideas. To the ideal of the empire the army remained loyal throughout the principate, although this loyalty came at length to be interpreted in the light of its own particular interests. Not only was the army the support of the power of the princeps; it was also the mainstay of the _pax Romana_ which endured with two brief interruptions from the battle of Actium to the death of Severus Alexander and was the necessary condition for the civilizing mission of Rome. IV. THE PROVINCES UNDER THE PRINCIPATE It is to the provinces that one must turn to win a true appreciation of the beneficial aspects of Roman government during the principate. As Mommsen(16) has said: “It is in the agricultural towns of Africa, in the homes of the vine-dressers on the Moselle, in the flourishing townships of the Lycian mountains, and on the margin of the Syrian desert that the work of the imperial period is to be sought and found.” In this sphere the chief tasks of the principate were the correction of the abuses of the republican administration and the extension of Graeco-Roman civilization over the barbarian provinces of the west and north. How well this latter work was done is attested not merely by the material remains of once flourishing communities but also by the extent to which the civilization of Western Europe rests upon the basis of Roman culture. *Number of the provinces.* At the establishment of the principate there were about thirteen provinces, at the death of Augustus twenty-eight, and under Hadrian forty-five. In the course of the third century the latter number was considerably increased. The new provinces were formed partly by the organization of newly conquered countries as separate administrative districts and partly by the subdivision of larger units. At times this subdivision was made in order to relieve a governor of an excessively heavy task and to improve the administration, and at times it proceeded from a desire to lessen the dangers of a revolt of the army by breaking up the larger military commands.