Three miles south of Windsor Castle, in the western exurbs of London, stands a 25-ton equestrian statue of King George III, cast from old cannons in the decade after his death in 1820. Dressed as Marcus Aurelius, in toga and laurel crown, he sits astride his charger, regal and oversize, honored if not revered for a reign that lasted almost 60 years, from the creation of the first British empire in the Seven Years' War through the final defeat of Napoleon.