Simplify the following text for a Grade 2 native English-speaking person.
Original: He was the son of Atreus and Aerope , and brother of Agamemnon king of Mycenae and , according to the Iliad , leader of the Spartan contingent of the Greek army during the War .
Simplified: He was the son of King Atreus of Mycenae and Aerope . He was the brother of Agamemnon .