The Orestaia is a group of three separate plays written by author Aeschylus. Agamemnon begins right at the tail end of The Iliad, which is the story of the Trojan War. Agamemnon has been away from home for a decade fighting to get his brother's wife back, and the watchman opens the play sighing wistfully for his master's return. I've always interpreted these opening lines somewhat differently than the previous educator—as we know by the end, Agamemnon's wife Clytemnestra is not a savory character. She has been scheming with Agamemnon's cousin to kill him in punishment for his father Atreus's sins (there is a long and complicated backstory to all of that, but in general the theme is the sins of the father are paid for by the son).

The watchman laments the last ten years, saying he has taken his orders from a "woman with a man's heart." This alludes to Clytemnestra's cruelty and habit of treating those below her like dogs. It also gives the reader a hint into Greek society—Clytemnestra has gone against social convention by choosing her husband (she has married her co- conspirator) and ruling while Agamemnon is away. The watchman, in only a few sentences, gives a pretty clear picture of the state of the kingdom: a wicked and cruel mistress, a missing king, and general anxiety about the state. Agamemnon's return gives the watchman hope, as he is a seen as a good man and good king.

Aeschylus' Agamemnon, first staged in 458 BCE, is the first play of the so-called Oresteia trilogy. The play opens with a watchman sitting on the roof of the palace. He has been waiting for a signal flare for a long time and expresses his exhaustion at waiting for so long for the return of Agamemnon from Troy. Most of his comments have to do with his sleeplessness and that he is essentially being worked like a dog. He also alludes to the fact that Agamemnon's wife has been waiting anxiously for her husband to return.

Once the watchman finally sees the signal flare indicating the fall of Troy and the return of Agamemnon, the watchman rejoices and looks forward to shaking Agamemnon's hand upon his return from Troy. The watchman, however, end his prologue on an ominous note that seems to foreshadow the horrors that await Agamemnon upon his return:

Had it voice,
The home itself might soothliest tell its tale;
I, of set will, speak words the wise may learn,
To others, nought remember nor discern. (E.D.A. Morshead translation).