The ancient Roman soldier constituted the basic, integral unit of one of history's most extraordinary and successful military systems. Between about 400 B. C. and A. D. 100, the legendary Roman army conquered the entire Mediterranean world, bringing Rome the mightiest empire the world had yet seen. For centuries afterward, Rome administered that world, spreading Roman culture and ideas far and wide; and after its empire collapsed in the fifth century, numerous elements of that culture remained ingrained, profoundly shaping the development of medieval and modern Europe. These far-reaching developments could not have occurred without the exceptional discipline, skill, courage, daring, and often sheer tenacity displayed by many generations of Roman military men.

The discipline, courage, and training of Roman troops is attested not only by their many successes on the battlefield but also by the surviving accounts of eyewitnesses...