The Attack on Camp Jupiter was a major battle in the Second Giant War, led by the giant Polybotes. A Giant Army victory would have been assured had it not been for the success of Frank Zhang's quest to rescue the god Thanatos and recover the Imperial gold weapons lost thirty years previously, and for the intervention of the Amazons, led by Queen Hylla Avila Ramírez-Arellano. In the end, the Greek demigod Percy Jackson worked with the Roman god Terminus to destroy Polybotes until his regeneration a month later. Following his victory, Percy was raised on a shield and named praetor of the Twelfth Legion, replacing the absentee Jason Grace.
Six months after his brother Porphyrion's rebirth, the giant Polybotes, natural enemy of the god Neptune, gathered his forces—composed of Cyclopes, centaurs, Earthborn, basilisks, karpoi, and the Gorgons—in San Francisco in preparation for an attack on Camp Jupiter. In order to ensure victory for their mother Gaea, his brother Alcyoneus's forces captured the death god Thanatos and chained him in Alaska so that Polybotes's forces couldn't die. These events were enough to involve two major gods, Juno Moneta (Juno the Warner) and Mars Ultor (Mars the Avenger).
The Queen of Olympus had seen how the war must go. She brought Percy Jackson, the son of Poseidon, to Camp Jupiter. Upon passing over the Little Tiber, Juno assumed her true form and warned the camp that on the Feast of Fortuna, goddess of luck, New Rome would be attacked by a legion of monsters. Later that same day, Mars arrived to warn the camp that Thanatos was captured and that a quest must be undertook to unleash Death. The god declared that his son Frank Zhang must go with Percy Jackson, but other than that he didn't care.
Shortly before heading off with Frank and Hazel Levesque, Percy was called in for a private meeting with Reyna. The two demigods discussed the army that would soon attack New Rome. Reyna admits that she was aware, but she forbid Octavian from releasing his auguries to the general public, hoping to avoid a panic. She declared that, with the disappearance of Jason Grace, they were going to need to a strong leader to oppose Gaea's forces. She offered the position to Percy, but the son of Poseidon turned her down, which surprised her.
As Percy, Frank, and Hazel set off for Alaska, the border god Terminus warned them to keep an eye out for a Gigante named Polybotes. Later, after facing a horde of karpoi, the demigods witnessed Polybotes and his army marching south, opposed by the goddess Iris along the way. Hazel insisted that they must warn the camp, but Percy replied that Reyna was already aware of that. Inside Iris's residence, Percy and Hazel sent an Iris message only to discover that Percy was right: at least Reyna and Octavian were already aware. This only went to show how desperate their situation was.
In Seattle, Hazel spoke with the Amazons, specifically Queen Hylla Avila Ramírez-Arellano and her deputy Kinzie. Hylla admitted that if she had any choice, she would aid her sister in defending Camp Jupiter. The work of former Queen Otrera was serving to impede her efforts. She agreed to discreetly aid Hazel and her friends in their escape, depending on the chance that they might be able to free Thanatos and allow her to kill Otrera permanently. Later, just before arriving in Alaska, Percy dreamed about Polybotes and the gorgon Stheno, preparing for the upcoming attack on New Rome. Polybotes that he wanted to particularly kill the blood of his sworn enemy, Percy Jackson, and use his blood to wake the Earth Mother.
Both missions, Hylla's and Frank's, ended with success. At Hubbard Glacier, Frank burned a portion of his firewood, using the "bonds of life," to release Death. Percy singlehandedly fought an army of Roman shades, including the late praetor Michael Varus. As Percy tumbled from the glacier, Frank used his shapeshifting gifts from his ancestor Periclymenus to defeat Alcyoneus, until Hazel finally slew him with her spatha, in Canada. In the end, Percy also lived, and he and his Roman allies returned to Camp Jupiter, custodian of the lost Imperial gold weapons.
By the time Percy, Frank, and Hazel arrived in California, the attack was already in progress and morale was low in the Legion.Reyna (on her pegasus Scipio) fought Polybotes himself while while the rest of the Twelfth, led by each cohorts centurions, engaged the army. Luckily, Percy, Hazel, Frank, the Cyclops Tyson and the hellhound Mrs. O'Leary arrived. Percy distributes Imperial Gold equipment to the 5th Cohort and the battle starts to turn in the favor of Camp Jupiter. Percy handshe legion's standard to the centurion Dakota, who promised to carry it with honor. As Tyson destroyed the Cyclops leader Ma Gasket, Percy attacks Polybotes. As the Gigant chases Percy, he unleashed an army of basilisks, which were destroyed by Frank (in weasel form).
Finally, at the border of New Rome, Percy struggles with Polybotes, trying to convince the god Terminus to help. The border god was reluctant, until Polybotes angrily demolished one of his statues. Incensed, Terminus agreed to help Percy destroy the Gigante. Polybotes arrogantly taunted Percy, until he learned that the statue he had offended was a god. Together, Percy and Terminus destroyed Polybotes. The Romans then raised Percy on a shield as their duly elected praetor. This victory healed the decades-old rift between the Romans and Amazons.
- Ma Gasket
- Polybotes (later resurrected)
- Unknown number of monsters and Romans
- Unknown number of Amazons
That night, following a long day of celebrations, Percy dreamed of Juno in the aspect he knew her in, Hera. Hera explained the mission that must take forth to ensure victory in the Giant War. She explained that Jason would soon be arriving in the Argo II with Leo Valdez, Piper McLean, and Annabeth Chase. Hera claimed that Annabeth had a task ahead of her and that she sincerely doubted her nemesis could handle it. Angrily, Percy sprayed the goddess with water.
The following day, June 25, the Argo II arrived, preceded by a message from Leo, asking the Romans not to strike them down. Percy served as the Greeks' ambassador in the Roman Senate. He vouched for Camp Half-Blood, asking the Romans to trust his old friends. This led to Jason's return and the subsequent reunification of the Greeks and Romans. Negotiations would have been met, if an eidolon had not—through Leo—shot up New Rome, erupting into the Second Demigod Civil War.
After tumbling into Tartarus on the Kalends of July, Percy and Annabeth were pursued by several old foes, including Polybotes, seeking revenge for his defeat at the hands of the son of Poseidon. Shortly after, he returned to the mortal world.