Here's what happened:
* Ares's Attack: Ares, angered by Percy's interference in his plan to steal the Master Bolt, sent a monstrous boar to kill him.
* Percy's Defense: Percy managed to dodge the boar's initial charges, but it was too powerful for him to defeat head-on. He realized the only way to survive was to use his newfound powers.
* Riptide to the Rescue: Percy summoned his sword, Riptide, and in a moment of courage and desperation, he thrust it into the boar's heart.
* The Boar's Demise: The boar let out a final roar and collapsed, its monstrous form turning into dust.
This event is significant because it marks Percy's first major victory against a powerful monster, showing his potential as a demigod and foreshadowing his future role as a hero.