On the evening of the fourth of July, the Hephaestus Cabin has the duty of making the fireworks. However, not wanting to settle for lame red and white fireworks, they anchor a small barge near the beach and shoot fireworks in such succsesion that they create moving images of greek battles and scenes in the sky. The fireworks are the main dating event for the campers of Camp Half-Blood.
The fireworks are said by Annabeth, who had seen them before, that they were the size of patriot missiles and were shot in such succsesion that they created frame by frame movies of greek scenes, the finale was a 100 foot tall Spartan fight which blasts into a shower of colors at the end. Scenes that are mentioned include: "Hercules killing the Nemean lion, Artemis chasing the boar, George Washington crossing the Delaware."
The fireworks are mentioned as one of the events passing during Percy's final days during camp, which are perfectly normal, for a strange reason. With the fireworks passing it means that The Demigod Files took place during the book, as supposed to in between The Battle of the Labyrinth and The Last Olympian, since the fireworks are during The Demigod Files as well as the battle.
The fireworks are mentioned as the main dating event at camp. Beckendorf was going to ask Silena Beauregard to the fireworks at a Capture the Flag game. The teams had the Aphrodite, Athena, Ares, Dionysus and the Demeter cabins against Percy's and Beckendorf's team. Beckendorf and Percy troop to the right flank near the opposing team's flag, yet during a fight with Myrmekes with Annabeth and Silena, they are caught, since they were on the opposing team. Afterwards, Beckondorf asks Silena to the fireworks and she accepts. Then, whilst Annabeth locks Percy in a cell, she says "See you at the fireworks?" and leaves.