Complex sentence: As the Greek rulers celebrate the capture of the Trojan beach, Agamemnon angers Achilles by taking Briseis and Achilles orders the Myrmidons to stay out of the war until Agamemnon begs Achilles to return.
Split into simpler sentences: As the Greek rulers celebrate the capture of the Trojan beach, Agamemnon angers Achilles by claiming Briseis for himself. Achilles, in retribution, orders the Myrmidons to stay out of the war until Agamemnon begs Achilles to return.