<P> In Greek mythology, Calchas (/ ˈkælkəs /; Ancient Greek: Κάλχας Kalkhas, possibly meaning "bronze - man"), son of Thestor, was an Argive seer, with a gift for interpreting the flight of birds that he received of Apollo: "as an augur, Calchas had no rival in the camp". He also interpreted the entrails of the enemy during the tide of battle . </P> <P> It was Calchas who prophesied that in order to gain a favourable wind to deploy the Greek ships mustered in Aulis on their way to Troy, Agamemnon would need to sacrifice his daughter, Iphigeneia, to appease Artemis, whom Agamemnon had offended . The episode was related at length in the lost Cypria, of the Epic Cycle . He also states that Troy will be sacked on the tenth year of the war . </P> <P> In the Iliad, Calchas tells the Greeks that the captive Chryseis must be returned to her father Chryses in order to get Apollo to stop the plague he has sent as a punishment: this triggered the quarrel of Achilles and Agamemnon, the main theme of the Iliad . Later in the story, Poseidon assumes the form of Calchas in order to rouse and empower the Greek forces while Zeus is not observing the battle . </P> <P> In Sophocles' Ajax, Calchas delivers a prophecy to Teucer suggesting that the protagonist will die if he leaves his tent before the day is out . </P>

When has calchas given agamemnon bad news before