Pausanias Description of Greece 1.32.6

[6] In Marathon is a spring [ pēgē] called Makaria, and what they say about it is as follows. When Hēraklēs left Tiryns, fleeing from Eurystheus, he went to live with his friend Keyx, who was king of Trakhis. When Hēraklēs departed the life of humans [ anthrōpoi], Eurystheus demanded his children. But the king of Trakhis sent them to Athens, saying that he was weak while Theseus was hardly powerless to protect them. The arrival of the children as suppliants [ hiketai] caused for the first time war between Peloponnesians and Athenians, since Theseus refused to give them up [= the children of Hēraklēs] at the demand of Eurystheus. And they say that an oracle [ khrēsmos] was given the Athenians that one of the children of Hēraklēs must die a voluntary death, or else victory [ nīkē] could not be theirs. Then Makaria, daughter of Deianeira and Hēraklēs, slaughtered [ apo-sphazein] herself and gave to the Athenians the upper hand [ kratos] in the war and to the spring [ pēgē] her own name.