In the journey to Camp Jupiter, Percy’s memory returns in full. With the return of his memory, Percy understands that the real war will “happen far away, in the homeland of the gods” (473). To stop Gaea, all the demigods—both Greek and Roman—will have to work with the gods to stop her.

Percy, Frank, and Hazel arrive at Camp Jupiter to find the battle already underway. Arion is too tired to take the gold weapons to the battlefield, but Tyson and Mrs. O’Leary are there with Ella. Percy instructs Tyson to put on Roman attire so the others will know he is on their side, tells Ella to hide, and hooks Mrs. O’Leary up to the chariot so that she can drag it to the legion.

Percy takes the Imperial gold weapons to the Fifth Cohort and joins the fight. The Fifth Cohort, with Hazel and Frank, takes on a group of centaurs. Percy sees the First and Second Cohorts struggling with Polybotes. Percy leads the Fifth Cohort to their aid. Percy lifts the eagle and cries, “Twelfth Legion Fulminata!” (482). Lightning flashes from the eagle and destroys the enemy’s centerline. Percy sends the Fifth Cohort to help the Fourth, and he takes on Polybotes himself.