Homer begins by asking the Muse to help him sing the story of the rage of Achilles. The outcome of Achilles’ anger is the will of Zeus, but it also killed a huge number of Achaean soldiers. The story opens in the ninth year of war between Troy and the Achaeans, when a plague has swept over the Achaean army. A priest of Apollo named Chryses comes to the Achaeans to ransom back his daughter, whom the Achaeans had captured and gave to the Achaean chief Agamemnon as a spoil of war. All the Achaeans advise Agamemnon to give up the girl, but Agamemnon flatly refuses.
Homer’s address to the Muse begins the idea that the Iliad is a poem inspired by the gods, an epic undertaking that will retrace a myth already well known to Homer’s ancient Greek audience. When Agamemnon’s refuses to give up Chryses’ daughter, Apollo provides an early example of divine intervention, setting an example of how the gods can quickly change the fortunes of men.
Chryses departs, but prays to Apollo to send down arrows of plague onto the Achaeans. Apollo hears his prayer, and the Achaeans begin to die from disease. Ten days later Achilles calls a meeting of the troops. He declares that unless Apollo is appeased they will have to abandon the war against Troy. The seer Calchas says that he can explain Apollo’s wrath, but only if Achilles promises to protect him after he explains. Achilles agrees readily, and Calchas tells them that Chryse's daughter must be returned and that a sacrifice must be made to Apollo.
Calchas’ interpretation of Apollo’s plague shows one way that the gods interact with mortals in the poem, giving them signs without making their intentions fully known. Apollo has the power to fate many men to death. Calchas’ plea for Achilles to protect him foreshadows the conflict between Agamemnon and Achilles.
Agamemnon protests, saying he prefers the girl to his wife, but gives in for the good of all. However, he insists that he must be repaid for his loss, or else he will be dishonored. Achilles tells him that all the treasure has already been divided, and that they will repay him later. Agamemnon refuses, saying that he will take the prize of any captain he pleases, including Achilles. Achilles is outraged, criticizes Agamemnon’s leadership, and threatens to sail home.
The dispute between Agamemnon and Achilles is primarily a question of honor. Because Agamemnon is the most powerful king, he believes that he is entitled to the largest share of the war’s spoils. Though Achilles’s kingdom is less powerful, he is known to be the strongest fighter, giving his words in meeting extra weight.
Agamemnon tells him that he doesn’t care if Achilles leaves, and that he will take Achilles’ own spoil of war, the girl Briseis, by force. Achilles captured Briseis himself and cares deeply for the girl. Achilles is seized by rage and thinks of killing Agamemnon on the spot, but the goddess Athena appears at his side and checks his anger, promising him a reward for his restraint. Instead, Achilles insults Agamemnon and declares that he will no longer fight for him. The elder captain Nestor tries to mediate the dispute, asking Agamemnon and Achilles to back down, but neither listens to him. Achilles storms off to his camp and Agamemnon organizes the sacrifice to Apollo.
Achilles considers Agamemnon’s threat to be deeply dishonorable, as Briseis was captured through Achilles’ skill in battle. In addition, Achilles seems to have a strong emotional attachment to Briseis. Athena’s appearance is the first time we see a god speak directly to a mortal. Her action curbs Achilles’ rage, calling into question Achilles’ free will in the moment.
Agamemnon calls two heralds and tells them to go to Achilles’ camp and take away Briseis. When they arrive, Achilles welcomes them and lets the heralds take Briseis away without a fight. He criticizes Agamemnon again and tells the heralds that the day will come when they will need his help. The heralds escort Briseis back to Agamemnon’s camp.
Weeping, Achilles prays to his mother Thetis, a sea goddess, to help him get revenge on Agamemnon. He says that because he knows his life will be short, he should at least have his honor. Thetis appears at his side, sensing his grief. Achilles explains the situation and asks his mother to plead with Zeus to take action. He notes that Zeus owes Thetis a favor, as Thetis once helped him escape a revolt of the other gods. Thetis laments Achilles’ fate, doomed to both heartbreak and a short life. She agrees to go see Zeus when he returns to Olympus in twelve days, and instructs Achilles to keep clear of the fighting.
By invoking his mother Thetis, Achilles sets his destiny into motion. Thetis loves her son, and knows that if she honors Achilles’ request, it will lead to his early death. However, by the same token, the fact that Achilles’ life is fated to be short means that his mother is more determined to give him glory. She knows Zeus, the highest god, will be able to help her.
Meanwhile, the captain Odysseus sails to the island of Chryses, returns the priest’s daughter, and conducts Agamemnon’s sacrifice to Apollo. The men feast and then sail back to the Achaean camp.
Odysseus’ sacrifice is necessary to appease Apollo and save the Achaean armies. The feast gives a sense of daily life and the routines used for sacrifices.
After twelve days, Zeus returns to Olympus. Thetis goes to see him and kneels before him, asking him to honor her son by granting the Trojans victory while Achilles remains out of the battle. Zeus is angered, and says that helping the Trojans would force him into a fight with his wife Hera, who supports the Achaeans. However, he agrees, and bows his head as a sign of promise. Thetis departs, and Zeus rejoins the other gods in assembly.
Zeus’ promise is described as something powerful that cannot be taken back: Achilles’ honor will be upheld. However, Zeus also indicates that Hera will fight against his promise, a sign of both the unsure nature of fate and the humanlike passions of the gods.
Although Zeus attempted to make his promise to Thetis in secret, Hera has seen everything. She taunts Zeus for trying to make secret plans, and tells him that she has seen him making a promise to Thetis. Zeus tells her not to meddle in his plans, and that there is nothing she can do to stop him from doing as he pleases. Hera is silenced by his fierce words.
For the first time, the gods are seen together and seem to resemble a family where husband wife bicker. While Hera is able to needle or hinder Zeus, it is clear that he is much stronger than she is, and that his promise will come to pass.
Hephaestus stands up in front of all of the gods, attempting to defuse the quarrel between his parents Zeus and Hera. He tells Hera that Zeus is far too strong, and gives a comic speech about his own fall from Olympus. The last time he tried to defend Hera, Zeus threw him off Olympus; badly injured, mortals nursed him back to health. The gods laugh and feast. As night falls, Zeus sleeps beside his wife Hera.
Hephaestus’ speech is an attempt to protect his mother Hera, with whom he is very close. His story is comic to the gods because although Zeus was able to injure him, Hephaestus is still immortal. To them, the idea of being nursed by mortal men is humorous.