Agamemnon is the first play in a trilogy, the Oresteia, which is considered Aeschylus' greatest work, and perhaps the greatest Greek tragedy. Of the plays in the trilogy, Agamemnon contains the strongest command of language and characterization. The poetry is magnificent and moving, with skillful portrayal of major and minor characters alike.
The play's mood carries a heavy sense of impending doom. From the Watchman's opening speech through the Chorus' foreboding words and Cassandra's prophesies, the drama prepares the audience for the King's murder. The actual act of violence occurs off-stage, a traditional practice in Greek tragedy. Thematically, the murder of Agamemnon must be understood in the context of three other acts of violence, all of which precede the action of the play.
The first significant violent development in the play is the theft of Helen and the Trojan War that followed; again and again, the Chorus declares that even the deaths following the conflict should be dropped at Helen's door. The second violent act is Agamemnon's sacrifice of his daughter Iphigenia, which justifies Clytemnestra's resolve to murder him. Perhaps the most vile display of violence is the terrible sin of Agamemnon's father, Atreus, who cooked his own brother's children and served them to him. This act justifies Aegisthus' role in the play. But in a broader sense, it is the source of the ancestral curse that pervades the trilogy, as one act of violence leads to another.
The title character, Agamemnon, appears only briefly, and comes across as a cold husband and arrogant king. Clytemnestra, with her icy determination and fierce sense of self-righteousness, is far more attractive to the audience; we sympathize with her for much of the play. However, her entanglement with the odious Aegisthus and her murder of the innocent hapless Cassandra remind us that, in the larger context of the trilogy, she is not an avenger but an adulteress and a murderer whose crime leads inexorably to Orestes' vengeance in the next play.