The story of the "Advance Wars" begins in the "Field Training" tutorial mode, with the nation of Orange Star in a war against the neighboring nation of Blue Moon, with Olaf as the Blue Moon Army commanding officer (CO). Olaf suddenly ordered an invasion of the Orange Star nation and is in battle with the Orange Star Army. The campaign continues the story that started in the tutorial. Nell, the "de facto" leader of the Orange Star COs, gives the player the duty of a tactical advisor for the Orange Star Army.