A Watchman, atop the roof of the palace in the Greek city of Argos, complains that he has spent so much time in this perch that he knows the night sky by heart. He is waiting for a beacon that will signal the fall of Troy, which has been besieged for ten years by a Greek army led by Agamemnon, the king of Argos. Agamemnon's wife, Clytemnestra, governs Argos in her husband's absence, and, while the Watchman says that she has "male strength of heart," (11) the absence of the king makes him fearful. "I sing," he declares, "only to weep again the pity of this house / no longer, as once, administered in the grand way" (16-18).
The beacon flares, signaling Troy's fall, and the Watchman leaps up and cries out with joy at the news, and rushes inside to tell the Queen. The Chorus, an assembly of Argos' oldest and wisest male citizens, comes onstage and discusses the history of the Trojan War. They recount how Agamemnon and his brother Menelaus, the king of Sparta, gathered a huge fleet and army to recapture Helen, Menelaus' wife, who was stolen by Paris, a Prince of Troy; and they discuss how the Greeks and Trojans have spent ten years wearing themselves out in battle. Meanwhile, the old men of Argos (the men too old to fight) are growing weaker and weaker in their old age.
Clytemnestra joins them, and the Chorus demands to know why she has ordered sacrifices to all the gods and celebrations throughout the city. Before she answers, they recall the terrible story of how the Greek fleet, on its way to Troy, was trapped in Aulis by unfavorable winds, and how Agamemnon learned that the winds were sent by Artemis, the goddess of the hunt. In order to appease her and sail on to Troy, Agamemnon was forced to sacrifice his daughter, Iphigenia; the Chorus describes in detail her pitiful cries for mercy as her father's men cut her throat.
The strength of the minor characters in Agamemnon distinguishes this play from a number of Aeschylus' other works. The Watchman, whose speech opens the play, is particularly noteworthy. His complaints about his tiresome duty and his worries over the state of the city--together with his obvious, sincere joy at the news of his king's victory--make him a realistic, multifaceted, human character. His combination of anticipation and foreboding, meanwhile, establishes the mood of the play; the King's return is an occasion for celebration, and yet a sense of fear looms over Argos, a premonition of terrible events waiting to happen.
The events in Agamemnon are only a small part of a much larger story, as the Chorus makes clear in its lengthy speech. Two women who do not appear in the play have a profound effect upon the events in Argos: Helen, Menelaus' wife, and Iphigenia. Helen's eloping with Paris catalyzes the entire Trojan conflict and its aftermath; throughout the play, the Chorus comments on how much suffering has occurred "for one woman's promiscuous sake" (62). Meanwhile, the sacrifice of Iphigenia is a cloud over the marriage of Clytemnestra and Agamemnon and ultimately leads to his murder.
The description of Iphigenia's murder undermines the audience's sympathy for Agamemnon. The killing offends our sense of proportion. While it is true that Artemis demanded her death if the fleet was to sail to Troy, did Agamemnon really have to kill his daughter to win a war to recover a single woman? Aeschylus paints a pathetic portrait of Iphigenia's violated innocence: "her supplications and her cries of father / were nothing, nor the child's lamentation / to kings passioned for battle . . . Pouring then to the ground her saffron mantle / she struck the sacrificers with / the eyes' arrows of pity . . ." (228-30; 239-41) Thus, even before Clytemnestra speaks, Aeschylus provides a reason for her to hate her husband.