"The boy must die. Be thrown down from the towering wall of Troy. Now, let it be done.
Laocoon was suspicious of the massive wooden horse and he didn't believe Sinon's tale. Because of his opposition Poseidon sent sea serpents to kill him. Because Lacoon wasn't able to voice his suspicions the Trojans brought the horse inside the city and were attacked.
With the death of Hector's son, Troy's last sacrifice was accomplished. Troy perishes and is gone forever.