Voldemort wins the war thanks to a change of sides. Andromeda and Nymphadora Tonks changed sides. With their help and knowledge of the order Voldemort was able to win the war. Few survived the battle all that was left of the order was Hermione and Harry (since Voldemort can't kill Harry). Harry was given as a present to the last Malfoy (Draco) and Hermione was given to the Black sisters.
18 parts