Okay, here is the storys
Both the forces of Sauron and of Lord Voldemort have been of interest to Palpatine, the dark emperor. Indeed, they both used a type of power that could easily be connected to the Dark Side. The Galactic Empire proceeded to contact them. After a rocky start, the emperor managed to broker an alliance between himself, Sauron, and Lord Voldemort. They then set out to crush The Rebel Alliance, Gandolf, Hogwarts, and anything else that stood in their way.
At the same time, however, the Rebel Alliance had discovered the realms of Middle Earth and the Magical World. Locked in a bitter war with the Empire, they desparately needed assistance, especially from the wizards of the two worlds, whos powers resembled those of a jedi. Sending down a small landing crew, Luke Sywalker, one of the only remaining Jedis, managed to convince the wizards of Hogwarts that their mutual survival depending on coorporation. The same was done for the wizards of Middle Earth.
The only way such a situation could end was the complete victory of one side, and the complete defeat of the other.
One final note
oth Palpatine and Luke have realized that the force and magic are greatly connected.
