Speaking only in regards to Cannae, the consensus is that they were exiled to Sicily and eventually joined Scipio Africanus' expedition to Carthage in the hopes of regaining their lost honor. From Gregory Daly's 'Cannae: The Experience of Battle in the Second Punic War', "In other words in Polybius' analysis virtually none of the infantry who fought at Cannae survived the battle. This certainly accords with his account of the Romans being surrounded and fighting until the last man fell, and indeed it would be bizarre if it were otherwise. It is clear, however, that his figures are too high as there were surely more survivors of Cannae than he allows for. It is unnecessary at this point to analyse the other sources, save to note that Livy's figures, which allow for 14,550 fugitives (Liv. 22.50.3, 54.1, 4), are supported by his later references to the Legiones Cannenses. According to Livy, the survivors of Cannae were sent to Sicily, where they made up two legions and were later reinforced by the defeated survivors of the first battle of Herdonea. These troops were not to be released from service and were forbidden to return to Italy until the war was over, consequently becoming perhaps the most experienced troops in the entire Roman army, and serving as the backbone of Scipio's African expeditionary force in 204. These 'legions' may in reality have been irregular hybrids, incorporating large numbers of Latin and Italian allies, rather than being exclusively Roman. As Livy points out, the fact that many of the troops which were transferred to Sicily were allies rather than citizens causes unrest among the allied communities (Liv. 27.9.1-4). Against this, Livy claims that when Scipio was organising his army to invade Africa, he brigaded the survivors of Cannae into two legions, each of 6,200 infantry and 300 cavalry, with the allied troops being brigaded seperately (Liv. 29.24.14)."