The Greeks assemble their troops at Aulis, to proceed against the city of Troy, and revenge the rape of Helen; but the fleet is detained in port by contrary winds. Calchas, the priest, after a prediction concerning the success of the expedition, declares that the weather will never be favourable till Agamemnon shall have sacrificed his daughter Iphigenia. She is immediately led to the altar for that purpose; but Diana, appeased by this act of obedience, carries away the maiden, and substitutes a hind in her place, on which a fair wind arises. Upon the Greeks landing at Troy, a battle is fought, in which Protesilaüs is killed by Hector, and Achilles kills Cygnus, a Trojan, on which his father Neptune transforms him into a swan.
His father Priam mourned him, not knowing that Æsacus, having assumed wings, was { still} living; Hector, too, with his brothers, made unavailing offerings[1] at a tomb, that bore his name { on it}. The presence of Paris was wanting, at this mournful office: who, soon after, brought into his country a lengthened war, together with a ravished wife;[2] and a thousand ships[3] uniting together, followed him, and, together { with them}, the whole body[4] of the Pelasgian nation. Nor would vengeance have been delayed, had not the raging winds made the seas impassable, and the Boeotian land detained in fishy Aulis the ships ready to depart. Here, when they had prepared a sacrifice to Jupiter, after the manner of their country, as the ancient altar was heated with kindled fires, the Greeks beheld an azure-coloured serpent creep into a plane tree, which was standing near the sacrifice they had begun. There was on the top of the tree a nest of twice four birds, which the serpent seized[5] together, and the dam as she fluttered around { the scene of} her loss, and he buried them in his greedy maw. All stood amazed. But { Calchas}, the son of Thestor, a soothsayer, foreseeing the truth, says, "Rejoice, Pelasgians, we shall conquer. Troy will fall, but the continuance of our toil will be long;" and he allots the nine birds to the years of the war. { The serpent}, just as he is, coiling around the green branches in the tree, becomes a stone, and, under the form of a serpent, retains that stone { form}.