As part of the peace treaty which ended the war between Rome and Clusium in 508 BC, Roman hostages were taken by Lars Porsena. One of the hostages, a young woman named Cloelia, fled the Clusian camp, leading away a group of Roman virgins. According to Valerius Maximus, she fled upon a horse, then swam across the Tiber. Porsena demanded that she be returned, and the Romans consented. Upon her return, however, Porsena was so impressed by her bravery that he allowed her to choose half the remaining hostages to be freed. She selected the young Roman boys, so that they could continue the war.