The Siege of Camp Half-Blood was a part of the conclusion of the Second Demigod Civil War that took place in The Heroes of Olympus series. Shortly after the war between the two camps, Gaea awoke leading to the Battle of Half-Blood Hill.
The Heroes of Olympus[]
The Blood of Olympus[]
When Nico di Angelo, Reyna Ramírez-Arellano, and Gleeson Hedge arrive at Camp Half-Blood, they find Roman patrols outside the border preparing Octavian's attack on Camp Half-Blood with onagers. After taking care of Michael Kahale, the son of Venus and Octavian's assisstant, Nico goes with Centurions Dakota and Leila to the front lines to have the fifth and fourth cohorts fight against Octavian. When the son of Hades spots Will Solace, Cecil Markowitz, and Lou Ellen Blackstone sabotaging the Roman’s Onagers, he joins them until they are discovered by the legacy of Apollo. Moments later the fifth cohort arrives and swears their loyalty to Reyna and turn on Octavian, who orders them to be put down. He then orders the onagers to fire on Camp Half Blood, but because they were sabotaged by Nico and the others, the onager shots missed and instead collided with each other.
Soon after that the Greek demigods, Chiron, Tyson and the Cyclops army, and the Satyrs and nature spirits stand there ground on Half-Blood Hill. Before the fighting can breakout, the daughter of Bellona returns the Athena Parthenos to the Greeks and peace is restored. However, moments later Gaea awakes and attacks.