The Battle of the Acropolis was the penultimate battle in the Second Giant War, in which the Greek and Roman demigods of the Argo II fought the Gigantes and Gaea's army in Athens.
Early Battle[]
Percy, Annabeth, and Piper were sent to the Acropolis first, as saboteurs to sabotage the giants' onagers. They were successful, but Percy and Annabeth were captured by the Giants.
The Gods' Arrival[]
While the battle was progressing, Reyna placed the Athena Parthenos on top of Half-Blood Hill, healing the gods' split personalities and ending the Second Demigod Civil War. As soon as that happened, the Olympians came down from the sky, ready for battle.