Menelaus, brother of the King of MycenŠ, had for his wife the most beautiful woman in the world, whose name was Helen; but she was stolen from him by a treacherous guest, Paris, the son of Priam, King of Troy, who carried her away with him to his home far over the sea.

Then Menelaus, in his anger and sorrow, asked all his friends to help him to bring back his wife, and to punish his treacherous guest, and all the chieftains of Greece came to his aid, for Troy was a wondrous strong city, and its walls had been built by Neptune, the god of the sea.

Foremost of all the chieftains was Agamemnon, King of MycenŠ, the elder brother of Menelaus; he was chosen to be the head of the whole array, and under him served Ulysses, the wise king of Ithaca, and Achilles, chief of the Myrmidons, whom no weapon could wound save in the heel; and many more of fame throughout the whole world.

The fleet came together at Aulis in the land of Bœotia; all were ready and eager to fare forth over the sea and fight against Troy; and a goodly sight it was to see the brass-beaked vessels and the brave warriors who crowded thick upon them.

But day after day passed by and the fleet lay still in harbor, for no breeze came to fill the sails. And all the chieftains were dumfounded, for their valor was of no avail, and their hearts were heavy within them; for they knew not wherefore their ships lay thus becalmed, and they feared lest the immortal gods did not will that Troy should fall.

At last they sent for Calchas, the wise seer, and asked if he could tell them the will of the gods.

And Calchas made answer: "The winds are withheld from you, O chieftains, by the will of Diana, the huntress of the woods. For King Agamemnon, once on a day, slew a stag within her sacred grove, and ever since she has hated him sore, and therefore she will not let you sail till her anger is appeased by rich offerings."

Then said King Agamemnon; "Since mine is the blame, let the expiation be mine also. Speak, Calchas: what offering will content the goddess, that the winds may come forth from their prison-house and our ships spread their sails and fare over the sea to Troy?"

All hearkened eagerly, for the face of Calchas was dark and terrible, so that every man feared to hear his answer.

"The goddess asks of thee the best and most beautiful of all that is thine," said the stern seer; "she asks the life of thy daughter Iphigenia."

A shudder ran through all who heard the fearful words. Menelaus, with a cry of sorrow and terror, came close to his brother and laid his hand on his arm, and Agamemnon the king stood in a tumult of agony, speaking no word for some little space.

At length the chieftain looked round upon his comrades, saying: "A hard fate is upon me, ye leaders of the Greeks. For either I must shed blood that is dearer to me than my own, or else our great array must lie here idle till the ships are rotten or the captains desert and leave us stranded."

Then said Menelaus to Calchas: "Is there no other way? Cannot the great goddess be appeased without this innocent victim?"

And Calchas made answer: "There is no other way."

Agamemnon, with bowed head, climbed slowly to his tent upon the hillside, and the rumor ran quickly through the camp that the wrath of Diana could only be turned away by the death of the fair and innocent maiden Iphigenia, the daughter of the king.

Then Agamemnon despatched a guileful message to his wife Clytemnestra, praying her to send their daughter Iphigenia quickly to Aulis, since Achilles, the noble chief of the Myrmidons, had asked leave to wed the maiden, and it must be done in haste, for the fleet was on the point of sailing.

When Clytemnestra heard her husband's message she was glad at heart, for the fame of Achilles was great, and he was brave and strong and beautiful as the immortal gods.

In haste was the maiden decked for her wedding and sent with the messengers of Agamemnon to the camp at Aulis.

And as Iphigenia was led into the camp she marveled greatly, for all who looked upon her were filled with pity, and cold fear touched the heart of the maiden as she passed through the silent and sorrowful host. The warriors were moved at the sight of her youth and innocence; but no man strove to save her from her fate, for without her death all their gathering together would be for naught. Within the tent of Agamemnon the stern seer Calchas awaited the destined victim. All was prepared for the sacrifice, and Agamemnon and Menelaus already stood by the altar. In haste was the maiden decked out—not for her bridal, but for her death.

Then they led her forth into the sunshine again, and she looked round upon the hillside and the blue sea where lay the idle ships; and when she saw her father standing by the altar she would have cried out to him and begged for mercy, but those who led her laid their hands upon her mouth. The poor child tried to win from her father one pitying glance, but Agamemnon hid his face in his mantle; he could not look upon the face of the child who was to be slain to expiate his sin. So there was no help for the beautiful and innocent maiden, and she was led to her death. But so great was the ruth of the Greeks that no man save the stern Calchas dared witness the terrible deed; and because they could not bear to believe afterwards that the maiden had indeed been slain there upon the altar, the tale went forth that at the last moment Diana had laid a hart upon the altar and had borne the maiden safely away to Tauris.

But in truth the cruel sacrifice was completed, and even as the flame leapt up on the altar the tree-tops swung and swayed, and ripples coursed over the glassy surface of the sea; the breeze for which the host had waited so long had been set free, and the warriors joyfully hoisted their sails and stood out of the harbor of Aulis on their way to the siege of Troy.

But now was Diana well avenged for Agamemnon's profanation of her grove. For, from the innocent blood of Iphigenia, uprose an avenger, destined to follow King Agamemnon and all his family till the dark deed had been expiated.

Long and grievous was the warfare before the walls of Troy; and it was not till the tenth year after his setting forth that tidings came that King Agamemnon was on his way home. All through those years his wife had nourished the hope of vengeance in her heart, both for the death of Iphigenia and for the falsehood that had made her send the maiden to the camp. So the king came home only to his grave. His wife received him with gracious words and with every sign of rejoicing; but ere night fell Agamemnon lay slain in his bath, where the dagger of Clytemnestra had smitten him down.

Next the Avenger of Blood put into the heart of Orestes, son of Agamemnon and Clytemnestra, a great hatred for the mother who had slain his father. He was far from home when the cruel deed was done, and it was long ere he returned; but when at last he came he smote his own mother and slew her.

After this deed of awe and terror the Avenger of Blood pursued Orestes, and drove him, a branded outlaw, from land to land. At length he fled to the sanctuary of the great goddess Minerva, and was at last permitted to expiate his guilt.

He had to seek a piece of land that was not made when he killed his mother, so he went to the mouth of a river where fresh soil was being formed by the sand that was brought down by the rushing flood. And here he was allowed to purify himself, and the Avenger of Blood left him, at last, at peace.