Heracleidae by Euripides

Iolaus, son of Iphiclus, and nephew of Hercules, whom he had joined in his expeditions during his youth, in his old age protected his sons. For the sons of Hercules having been driven out of every part of Greece by Eurystheus, he came with them to Athens; and, embracing the altars of the Gods, was safe, Demophoon being king of the city; and when Copreus, the herald of Eurystheus, wished to remove the suppliants, he prevented him. Upon this he departed, threatening war. Demophoon despised him; but hearing the oracles promise him victory if he sacrificed the most noble Athenian virgin to Ceres, he was grieved; not wishing to slay either his own daughter, or that of any citizen, for the sake of the suppliants. But Macaria, one of the daughters of Hercules, hearing of the prediction, willingly devoted herself. They honored her for her noble death, and, knowing that their enemies were at hand, went forth to battle. The play ends with their victory, and the capture of Eurystheus.