This book starts on Mount Olympus. Zeus calls an assembly of the gods because he is angry about what is going on near Troy. He accuses Athena and Hera of protecting Menelaus and Aphrodite of protecting Paris. These three goddesses are essentially still battling for the golden apple He announces that because Paris left the battle the victory should go to Menelaus. He then asks the assembled deities whether the war should continue or should the wealth and Helen be handed over to Menelaus. Hera gets very angry at the prospect of the Greeks being slighted, Zeus becomes very upset with Hera and asks her if she remembers all the sacrifices the Trojans have made on her behalf and tells her to do as she pleases but to beware:
"Whenever I am bent on tearing down some city Filled with men you love - to please myself - Never attempt to thwart my fury, Hera give me my way. For I, I gave you this All of my own free will but hardly willing. No, Of all the cities under the sun and starry skies, wherever men who walk the earth have dwelled, I honor sacred Ilium most with my immortal heart."Book 4, lines 47-54
Hera offers the Greek cities of Argos, Sparta and Mycenae in exchange and appeals to Zeus so that they may yield to each other. They decide that the Trojans are going to break the truce for a temporary triumph. Zeus sends Athena, flung like a falling star, to cause this.
Athena, disguised like a Trojan, finds the archer Pandarus to shoot an arrow at Menelaus. Pandarus shoots his arrow at Menelaus and hits. This arrow pierces Menelaus' clothing but does not wound him fatally, even though the blood comes gushing out. Agamemnon swears that Priam and the Trojans must die because they have broken an oath. Menelaus speaks to his brother and tries to calm him, pointing out that the wound is not fatal Agamemnon calls the healer Machaon to tend to Menelaus.
Agamemnon, meanwhile, stirs up the Greeks. He yells at the Greeks who are running from the ensuing battle, calling them cowards. Then, he goes from captain to captain encouraging them and telling them that Zeus won't protect the Trojans because they are oath breakers. He tells Idomeneus, who is strong as a boar, to "Drink deep of battle."Book 4 line 301
The Greek army moves forward like a heavy surf and the Trojans are like flocks of sheep. Ares inspires them and the armies clash. Antilochus kills the first Trojan, whom a companion attempts to save only to be cut down by Agenor. Diomedes kills a man, followed by Odysseus' first kill. The Trojans, with Hector, begin to move back, frightened by the spectacle, but Apollo inspires them to maintain their position. The two lines clash and intermix in war.
