The Iliad is saturated with allusions and references that we may overlook because we focus on parts of the poem that feel familiar and that fit with the popular narrative about what it means.
One example from the first sentence that I wonder about is “the will of Zeus was accomplished.” Why would Zeus want the heroes to die? An obvious answer emerges after we learn of Thetis’ request of Zeus, and his promise to honor her son, Achilles. Another interesting possibility comes via Hesiod. According to his “Works and Days,” the heroes, because they were sons or favorites of gods and goddesses, caused strife among the Olympians (as we see throughout the poem). These conflicts among the immortals threaten the stability of the pantheon and, of special concern to Zeus, his rule. The Trojan war is an opportunity to kill off the heroes (both Greek and Trojan) and remove the threat.
Integrating that line of thought, Achilles’ wrath—μηνιν/ménis in Greek, suggesting divine anger that is lasting—acquires added layers of meaning. Unlike Agamemnon, whose parents were both mortal, Achilles is part divine (his mother is the goddess Thetis). Her concern for Achilles’ honor causes her to supplicate to Zeus, which he knows will lead to strife with Hera, since she is on the side of the Greeks and does not want to see them slaughtered. This is not a story of good guys vs. bad guys. Zeus’ son, Sarpedon, fights on the Trojan side as does Aphrodite’s son Aeneas.