After Agamemnon says that Menelaus is victor after his fight with Paris, Athena persuades Pandarus to shoot an arrow at Menelaus. This event impacts the war because it broke the truce and instigated the war.
Paris Kills Achilles
After Achilles leaves the war, Patroclus takes his armor and fights for him to pretend to be Achilles. He fights Hector for Achilles, and Hector ends up killing Patroclus. This event is significant because after Achilles finds out Hector killed Patroclus, he decides to rejoin the war to avenge Patroclus.
Trojan Horse
After Patroclus' death, Achilles rejoins the war in order to avenge his friend. After he finds Hector, he begins to fight Hector and kills him. This is significant to the Trojan War because the Trojans lost their strongest fighter and this makes it easier for the Greeks to win.
The Sacrifice of Astyanax
After Achilles kills Memnon, Paris shoots an arrow towards Achilles, but Apollo guides the arrow towards his heel and this kills Achilles. This is significant to the war because Achilles, the Greek's strongest warrior, is dead, so now both sides lost their strongest warriors.
After the Greeks retreated, they gave the Trojans a wooden horse with Greek soldiers inside, claiming it is an offering for Athena. This event impacts the war because this ambush led to the death of many Trojan soldiers which led the Greeks to victory.
After the Greeks took over Troy, Astyanax, Hector's son, had to be sacrificed in order to end the war. After his sacrifice, Troy is officially gone and the war ends.