The Elf War (エルフ戦争, Erufu Sensou?) is the first campaign quest in Sword Art Online, spanning numerous chapters that take place from the 3rd Floor of Aincrad to the 9th Floor of Aincrad. At the beginning of the quest, the players must choose to either support the forest elves or the dark elves, thus branching the campaign into two main paths with different quests. The campaign quest plays a prominent role in the Progressive Arc.