Daenerys Targaryen has to conquer all of Middle Earth.
She gets:
10,000 Unsullied
2,000 Second Son mercenarys
100,000 Dothraki Cavalry
20,000 freed slaves for labor etc
Her 3 Dragons
Her forces occupy the Shire. They "win" if they defeat Mordor. Time is 1 year before LOTR starts.