To the general rule of propagation by regal edict or by bloodshed there were a few partial exceptions. Vladimir, the first Christian king of the Russians (980), destroyed the old monuments and images in the usual fashion; but under the auspices of his wife, the sister of the Byzantine emperor, Greek missionaries set up many schools and churches, and the kingdom seems to have been bloodlessly Christianized within three generations. It accordingly remained Christian under the two and a half centuries of Mongol rule, from 1223. Elsewhere the conversion of the Slavs was a process of sheer monarchic violence, as in Scandinavia. Always it was the duke or king who was "converted," and always his propaganda was that of the sword. Through three reigns (870-936) heathen Bohemia was bedevilled by dukes who coerced their subjects with the Church's help; a pagan prince who led a successful revolt, but was overthrown by a German invasion, lives in history as Boleslav the Cruel; and an equally cruel successor, who with German help used the same means on behalf of Christianity, figures as Boleslav the Pious (967-999). The same process went on in Poland; the converted duke (967), backed by his German overlords, seeking to suppress pagan worship with violence and meeting violent resistance. So among the Wends, who were also under German vassalage, the missionary was seen to be the tool of the tyrant, and the cause of paganism was identified with that of national independence. After generations of savage struggle, Gottschalk, the pious founder of the Wendish empire, was overthrown (1066) and put to death with torture. So in Hungary, where king Stephen (997-1038) combined slaughter with better propaganda, the king's death was followed by a desperate pagan revolt, which was twice renewed under his son.