Agamemnon was a king whose main fame is in Greek mythology (fiction stories). Think of it much like Shakespeare writing his famous plays about English kings of earlier days. The story about the king concerns the real place called Mycenae between the Greek cities of Argos and Corinth. He had a brother called Menelaus who had a wife called Helen. Now Menelaus was away from home, and at this time the gods introduced his wife, Helen to a hero called Paris, who lived in the city of Troy. Paris and Helen fell in love and Paris took her back to Troy.

Now Menelaus was not happy about this and asked Agamemnon to send an army to Troy to get her back. This resulted in the ten-year long Trojan War, the one which the Greeks eventually won by fooling the Trojans to take a wooden horse full of Greek soldiers inside their city walls. Eventually Paris was killed, Menelaus got Helen back, and Agamemnon took another beautiful maiden, Cassandra, back from Troy to his palace as part of the spoils of war. However, no sooner had he got there than he was murdered.

This is all typical of Greek myths and mixes fact and a good bloodthirsty plot.