Why does Achilles re enter the war?

Achilles re-enters the war primarily due to the death of his close friend Patroclus, who is killed by Hector while wearing Achilles' armor. Consumed by grief and rage, Achilles seeks revenge against Hector and the Trojans. His desire to avenge Patroclus and restore his honor drives him back into battle, marking a pivotal moment in Homer's "Iliad." This decision underscores themes of friendship, honor, and the consequences of pride.