Patroclus was Achilles’ close friend. The news of his death devastated the hero. He mourned beside the body, beating the ground and crying so loudly that Thetis (Achilles’ mother) came to comfort him. Then the grief gives way to anger, and Achilles craves vengeance.
Achilles was offended by Agamemnon and refused to fight on the Greek side. As he predicted, the Achaeans were losing the Trojan war. Patroclus decided to disguise himself as Achilles and lead the Myrmidon army. Achilles warned him not to follow the Trojans to the city walls and limit himself to driving the enemies off the Achaean ships. Unfortunately, his friend did not follow his advice.
Antilochus brought the news of Patroclus’ death to Achilles. The hero plunged into despair. He smeared himself with ash in moral pain, touching his friend’s dead body. Then he promised to fast until he killed Hector and revenged for Patroclus’ death. This wrath gave him the power to collect himself from the grief and return to the battle.
Achilles understood that it was partially his fault that Patroclus died. First, he refused to participate in the war despite multiple requests to change his mind. Second, he gave Patroclus his armor and horses to raise the soldiers’ morale. It was unfair, as he could do it by himself. But it was too painful for Achilles to admit these facts. He blames the horses that they did not return Patroclus alive and seeks bloody vengeance.