The Achaean (Greek) fleet was preparing to go to war against Troy and had amassed in Aulis. While there, Agamemnon, the leader of the expedition, killed a deer in a grove sacred to the goddess Artemis. She punished him by interfering with the winds (either by becalming them or by blowing the ships back into port) so that his fleet could not sail to Troy. The seer Calchas revealed that in order to appease Artemis, Agamemnon must sacrifice his eldest daughter, Iphigenia. Agamemnon at first refused, but, under pressure from the other commanders eventually agreed.
I was listening to a conversation about Antigone on The Partially Examined Life podcast last week in preparation for True Detective talk with Fuller, and in focusing on duty to the gods versus family, the example of Agamemnon came into play. He is known (mythologically) for sacrificing his daughter in order to get safe passage to travel for war, and so then to heighten their chances of winning the war against Troy. This season’s Game of Thrones placed Stannis Baratheon in the exact same bind, and he made the same brutal choice. Sacrificing his daughter was widely criticized as gratuitous and ill-suited to his character. After all, his loyalty to his daughter was made clear. But so too was his loyalty to the gods, or at least to the enchantress Melisandre, who presents herself as a stand-in for the gods. Stannis chooses Melisandre’s command and his own ambitions for victory at war, which could be argued as him choosing the fate of his country (and family still) over the fate of his daughter. Or he’s just selfishly seeking his own power, which is fairly silly if it’s coming through ostensibly divine means.
Anyway, not to justify the horrifying decision, but there is a mythological precedent (and, of course, history offers us no shortage of horrors). GoT cannot follow suit with this possible allusion, however. We might have expected Stannis to be murdered by his wife for his decision, but she hung herself, which may have been a worse death for Stannis to experience.
Shout-out to Wikipedia for the opening quote, from the Iphigenia page.