These great armaments had curiously contrasting fortunes in the third century and then the second. The first two Punic Wars were almost ruinously costly in lives. Fleets in the First Punic War were serious risks, thanks to nautical inexpertness and (occasionally) enemy skill. Polybius’ naval figures, or some of them, have been suspected, but heavy ship - and crew-losses did occur, as mentioned above. Losses at sea hit the Italian socii especially hard, with the maritime allies providing most of the crews.
In the Second Punic War, it was Roman armies which suffered catastrophes, not only in Italy but also in Cisalpine Gaul and Spain. Even if Roman losses at Cannae, for instance, are estimated downwards (not entirely convincingly) to 30,000 killed besides the 10,000 captured - and likewise Appian’s claim (Pun. 134.635) that Hannibal destroyed 400 Italian cities and slew 300,000 enemies - yet the Italian peninsula and especially its southern half suffered badly from 15 years of warfare. Roman territory itself, outside Campania, was not heavily harmed after 217: yet the census of 203, carried out with particular care (Livy 29.37.5-6), returned only 214,000 citizens (though it did omit several thousand now-disfranchized Capuans and other Campanians). The impact on the loyal Italian populations must have been proportionately harsher, while those who had defected not only had to provide forces for Hannibal’s war-effort but later suffered for this at the Romans’ hands.5
The wars following were a revolutionary contrast. None in the East lasted more than four years. Roman casualties were far fewer: 700 killed, as against 8,000 Macedonians, at Cynoscephalae in 197, in which Sp. Ligustinus no doubt fought (Polybius 18.27.6; Livy 33.10.7); allegedly 324 at Magnesia in 190, where Antiochus III was crushed (Livy 37.44.2); and, Livy affirms, 100 - mostly Italian socii - at Pydna in 168, where 20,000 Macedonians died (44.42.7-8). Defeats could occur - a notable setback at Callicinus in 171 against the Macedonians, for instance (42.57-60) - but none was shattering. There were few naval actions and no major disasters. Even allowing for deaths from wounds, skirmishes, and ailments, Roman forces in eastern wars must have come to feel almost damage-proof as well as invincible.
Although Spanish wars after 201 had fewer clear-cut endings - but instead much marching, many sieges, and opponents widely spread out and frustratingly resilient - Roman forces were smaller (usually a legion in either province), losses much lower, and a quarter-century, from 179 to 154, largely peaceful. Other second-century wars were small-scale, like the intermittent flare-ups in the Ligurian Mountains of northern Italy, in Sardinia and Corsica, and across the Adriatic in Illyria and Dalmatia; often enough, they were provoked by a general chasing booty, slaves, and gloria.