Agamemnon was the son of Atreas (son of Pelops) and Aerope, king of Mycenae, brother of Menelaus King of Sparta.. After Pelops death Atreas was the rightful king of Mycenae but was killed and usurped by his younger brother Thyestes. Agamemnon and Menelaus later defeated Thyestes and reclaimed the throne. Agamemnon lead the allied troops in the Trojan war after Helen wife of Menelaus was abducted by Paris son of Priam. (note that both sides in the Trojan war were Greek). He returned 10 years later and was murdered by his wife Clytemnestra in revenge for his infidelity and the attempted sacrifice of his daughter Iphigenia.