Back at the ships, Achilleus sees the Achaians fleeing back down the plain. He fears the worst.
He is worried because of a prophecy his mother once told him—that, while he was still alive, the best of the Myrmidons would die. Now Achilleus interprets this to mean Patroklos.
Now Antilochos reaches Achilleus and, in tears, delivers his message.
Overcome with grief, Achilleus pours soot and ashes on his head and clothes, defiling himself.
Then he falls on the ground like a dead man.
The captive women among the Myrmidon dwellings hear him and come over. They start wailing around him.
Meanwhile Antilochos holds Achilleus's hands—to make sure he doesn't kill himself in his grief.
At this point, Achilleus lets out a terrible cry. It is so loud that it reaches his mother Thetis, where she sits at the bottom of the sea.
Thetis comes to see her son, followed by a train of nymphs. Thetis laments that there is nothing she can do for Achilleus—he is doomed—but she will go anyway.
The nymphs make a circle around him on the beach, while Thetis cradles Achilleus like an infant, asking him what the matter is. She reminds him that, now that the Achaians have gotten their butts kicked, Zeus has granted all of Achilleus's wishes.
But Achilleus doesn't think any of that is worth it now that Patroklos is dead.
In fact, Achilleus now wishes he had never been born. He says he has lost the will to live—unless he can kill Hektor.
Thetis reminds Achilleus that he is now doomed to die: it is his fate that he will die soon after Hektor.
Achilleus says, "I don't care. Let me die then."
He curses the rage that made him fight with Agamemnon. Now he says that he'll patch things up with the Achaian king. Now it's time for killing some Trojans.
Thetis says, "Fine. But you still don't have any armor—Hektor stole it from Patroklos. At least wait until tomorrow. Then I'll bring you some new armor from the gods."
She sends the nymphs back under the sea and heads off to see Hephaistos—god of fire and metal-working—on top of Mount Olympos.
Meanwhile, on the field, the battle for Patroklos's corpse rages on inconclusively.
Iris, messenger of the gods, comes down from Olympos and tells Achilleus to go and rescue Patroklos.
He protests that, first of all, he has no armor, and, second of all, he promised not to fight until his mom comes back with more.
But Iris says, "Just go out to the trench and show yourself to the Trojans. They'll be so afraid to see you that they'll just turn tail and run."
Achilleus complies. But when he gets to the trench, Athene hangs Zeus's shield on his shoulder. Then she crowns his head in a flaming cloud. Not too shabby.
Achilleus lets out a huge cry—which Athene echoes.
Together, they make three cries in total. The combined effect of this infernal—er, that is, divine—racket is to drive all the Trojans off in terror.
The Achaians use this opportunity to bring Patroklos back.
Achilleus laments over him.
Then night comes.
In the Trojan council, Poulydamas worries about the consequences of Achilleus rejoining the action. He argues that they should pull back within the city's walls.
But Hektor is having none of it—not after all that they've (i.e., he) has accomplished.
"What if it was Achilleus?" He says. "I'll never run from him." (Bear this statement in mind when you get to Book 22.)
Hektor says they should stay on the plain, and the other Trojans agree.
Meanwhile, the Achaians are lamenting Patroklos. Achilleus leads the lament.
He is torn by grief that he couldn't bring Patroklos home safe to his father, as he promised. Now they will both die at Troy.
Achilleus swears that he won't bury Patroklos until he has killed Hektor.
Then he commands his comrades to wash and anoint Patroklos's corpse.
From Olympos, Zeus and Hera are watching what's going on.
Meanwhile, Thetis arrives in Hephaistos's workshop.
There, she is greeted by Hephaistos's wife, the goddess Charis (her name could be roughly translated as "Sexiness"). Charis then gets Hephaistos.
Hephaistos is glad to see Thetis. He remembers how she once helped him when his mother Hera threw him off Mount Olympos, disgusted that he was lame. He asks her what he can do for her.
Thetis laments the imminent death of her son and explains the whole situation.
Hephaistos says, "I also wish I could save him from death. As for the armor problem? That's no problem at all."
He tells her to wait in the sitting room while he goes off to his workshop.
There, with the help of his mechanical equipment, he first fashions a magnificent shield.
He decorates the shield with a representation of the entire world—bounded by the heavenly bodies and the ocean. Within these boundaries, he shows the polarities of human life: war and peace, city and country, conflict and celebration.
(Alexander Pope's celebrated eighteenth century translation of the shield passage may be read here.)
Then Hephaistos makes the rest of the armor and gives it to Thetis. She takes it down to Troy.