Roman army of the mid-Republic placed unprecedented strains on Roman manpower, not least on the Order of Knights and the First Class of commoners which provided the cavalry. During Hannibal's apocalyptic march through Italy (218–216 BC), thousands of Roman cavalrymen were killed in the field. The losses were especially serious for the equestrian order, which also provided the army's senior officers. Livy relates how, after Cannae, gold rings (a badge of knightly rank), recovered from the corpses of Roman knights formed a pile one "modius" (about 9 litres) large. In the succeeding years 214–203 BC, the Romans kept at least 21 legions in the field
Sanitation in ancient Rome sanitation artifacts of the ancient world. Most sources believe it was built during the reign of the three Etruscan kings in the sixth century BC. This "greatest sewer" of Rome was originally built to drain the low-lying land around the Forum. It is not known how effective the sewers were, especially in removing excrement. From very early times the Romans, in imitation of the Etruscans, built underground channels to drain rainwater that might otherwise wash away precious topsoil, used ditches to drain swamps (such as the Pontine Marshes), and dug subterranean channels to drain marshy areas. Over time, the Romans