Thetis presents Achilles with the armor that Hephaestus has forged for him. She promises to look after Patroclus’s body and keep it from rotting while Achilles goes to battle. Achilles walks along the shore, calling his men to an assembly. At the meeting, Agamemnon and Achilles reconcile with each other, and Agamemnon gives Achilles the gifts that he promised him should Achilles ever return to battle. He also returns Briseis.

Achilles announces his intention to go to war at once. Odysseus persuades him to let the army eat first, but Achilles himself refuses to eat until he has slain Hector. All through breakfast, he sits mourning his dear friend Patroclus and reminiscing. Even Briseis mourns, for Patroclus had treated her kindly when she was first led away from her homeland. Zeus finds the scene emotionally moving and sends Athena down to fill Achilles’ stomach with nectar and ambrosia, keeping his hunger at bay. Achilles then dons his armor and mounts his chariot. As he does so, he chastises his horses, Roan Beauty and Charger, for leaving Patroclus on the battlefield to die. Roan Beauty replies that it was not he but a god who let Patroclus die and that the same is fated for Achilles. But Achilles needs no reminders of his fate; he knows his fate already, and knows that by entering battle for his friend he seals his destiny.

While the Achaeans and Trojans prepare for battle, Zeus summons the gods to Mount Olympus. He knows that if Achilles enters the battlefield unchecked, he will decimate the Trojans and maybe even bring the city down before its fated time. Accordingly, he thus removes his previous injunction against divine interference in the battle, and the gods stream down to earth. But the gods soon decide to watch the fighting rather than involve themselves in it, and they take their seats on opposite hills overlooking the battlefield, interested to see how their mortal teams will fare on their own.

Before he resigns himself to a passive role, however, Apollo encourages Aeneas to challenge Achilles. The two heroes meet on the battlefield and exchange insults. Achilles is about to stab Aeneas fatally when Poseidon, in a burst of sympathy for the Trojan—and much to the chagrin of the other, pro-Greek gods—whisks Aeneas away. Hector then approaches, but Apollo persuades him not to strike up a duel in front of the ranks but rather to wait with the other soldiers until Achilles comes to him. Hector initially obeys, but when he sees Achilles so smoothly slaughtering the Trojans, among them one of Hector’s brothers, he again challenges Achilles. The fight goes poorly for Hector, and Apollo is forced to save him a second time.

Although Achilles has reconciled with Agamemnon, his other actions in Books 19 and 20 indicate that he has made little progress as a character. He still demonstrates a tendency toward the thoughtless rage that has brought so many Achaeans to their deaths. He remains so intent on vengeance, for example, that he initially intends for the men to go into battle without food, which could prove suicidal in a form of warfare that involves such great expenditures of physical energy. Similarly, on the battlefield Achilles demonstrates an obsessive concern with victory—to the exclusion of all other considerations. He cuts down the Trojan Tros even though Tros supplicates him and begs to be saved; it is apparent that Achilles has done little soul-searching. Although he reconciles himself with the Achaean forces, this gesture doesn’t alleviate his rage but rather refocuses it. He now lashes out at the Trojans, expressing his anger through action rather than through pointed refusals to act. Burning with passion, Achilles rejects all appeals to cool-headed reflection; the text compares him to an “inhuman fire” and, when he dons his shining armor, likens him to the sun (20.554). This imagery recalls his portrayal in Book 1 as “blazing Achilles” (1.342).

Indeed, Achilles’ internal dilemma as a character remains largely the same as in the beginning of the epic. Achilles has known throughout that his fate is either to live a short, glorious life at Troy or a long, obscure life back in Phthia. Now, as before, he must choose between them. Although he still feels torn between the two options, the shock of Patroclus’s death has shifted the balance in favor of remaining at Troy. There is little reason to believe that Achilles would have made up his mind without such a powerful catalyst for his decision.

These books of the poem concern themselves not only with the motivations and consequences of characters’ actions but also with the forces at work outside direct human agency. In particular, Agamemnon speaks of the powers of Zeus and Fate, blaming them for his stubbornness in the quarrel with Achilles. He notes that many have held him responsible for the destruction that his insult to Achilles has caused, but he insists that his earlier “savage madness” was driven into his heart by force (19.102). He also cites the force of “Ruin,” a translation of the Greek word Ate, which refers to delusion and madness as well as to the disaster that such mental states can bring about (19.106). But Agamemnon and other characters throughout the epic describe Ruin not as a mortal phenomenon but as something external to human psychology; ruin is described as a sentient being in and of itself. In Book 9, for example, Peleus describes Ruin as a woman, “strong and swift,” coursing over the earth wreaking havoc (9.614). Here, Agamemnon refers to Ruin as Zeus’s daughter, gliding over the earth with delicate feet, entangling men one by one, and even proving capable of entangling Zeus himself.

Another force repeatedly invoked here and throughout the Iliad is Fate. Despite the constant references to it, however, we never attain a clear sense of Fate’s properties. The first few lines of the poem suggest that the will of Zeus overpowers all, yet at times Zeus himself seems beholden to Fate. In Book 15, for example, he agrees to cease his aid to the Trojans because he knows that Troy is fated to fall. At other times, Zeus and Fate appear to work cooperatively, as in Book 20, when Zeus rallies the gods to stop Achilles from sacking Troy before its fated time. But one wonders to what extent this Fate is really fate at all, if Achilles can so easily preempt it. Other questions arise in Poseidon’s discussion of Fate, for he justifies saving Aeneas from Achilles on the grounds that Aeneas is fated to live. This reasoning is paradoxical, for if Aeneas is fated to live, he should not need rescuing.

Ultimately, the Iliad doesn’t present a clear hierarchy of the cosmic powers; we are left uncertain as to whether the gods control Fate or are forced to follow its dictates. The external forces of Fate, Ruin, and the gods remain as obscure as the inner workings of the human psyche. Thus, while the poet and his characters may attribute certain events to a personified Fate or Fury, such ascriptions do little to explain the events. Indeed, they achieve quite the opposite effect, indicating the mysterious nature of the universe and the human actions within it. To invoke Ruin or the gods is to suggest not only that certain aspects of our world lie beyond human control but also that many phenomena lie beyond human understanding as well.