§ 38. The main strength of a Roman army was in the legionary infantry. Of these, naturally, then, we have the most satisfactory accounts. About the auxiliary troops, cavalry and infantry, we have already spoken (§§ 17, 18). Of the legionary, we must now speak more in detail.
§ 39. In the earlier days of the republic the army was a compulsory levy of all the able-bodied male citizens of suitable age. None but Roman citizens were admitted to the legion. All Roman citizens must serve. At the close of the campaign the troops were disbanded, and returned to their homes and their usual avocations. Thus the army was a body of citizen soldiers, or militia.
But with the great increase in the number of citizens, especially after the social war, only a part were needed for military duty; and at the same time a plenty were found who were willing to enter the service, led by hope of gain and glory. So the armies became less and less a levy of citizen soldiery, and more and more a body of mercenary volunteers. From this fact certain results speedily appeared. As the Roman army grew to be a disciplined organization of professional soldiers, it became all the more effective ; and the men were the more readily attached to their chosen leader. Meanwhile the peaceful citizens who remained at home, to a great degree lost that military spirit and knowledge which had always before characterized the Roman people. Thus the way was paved rapidly and surely for the coming of a military despotism.