Laocoon believed the massive wooden horse known as the Trojan horse had men in it who would destroy the city of Troy. Laocoon was right, of course, but he was no more trusted than the prophetess Cassandra who also warned the Trojans against the horse.
Laocoon was a priest of the sea god Neptune, but this didn't save him from divine punishment when he thrust a sword into the side of the wooden horse. Ostensibly, the horse was an offering to the goddess Athena/Minerva. As punishment, Laocoon and his two son were strangled by serpents from the sea.
The Trojans considered this punishment a sign that Laocoon had displeased the god whom he served. They also believed it showed that the wooden horse was sacred, so they wheeled it into the city. The inevitable result was a Greek victory and Troy in flames.
