Psychological historians will point out that things started to go terribly wrong with Ivan after the death of his beloved wife, Anastasia Romanov, or they might point to the fact that he enjoyed torturing animals when he was a kid. Regardless, Ivan set out to break the power of the nobility, the former princes and landowners, called the Boyars. They were the last link to princely rule, and after an odd episode that saw him briefly abdicate, Ivan returned to Moscow and declared that he had the right to punish all traitors and evildoers. To help him in this effort, Ivan created the Oprechniki, a corps of secret police who rode around on black horses wearing all black, whose job it was to hunt down and destroy any enemies of the Tsar. See also Nazgul and Dementors. So this was the first of Russia's purges, and over the latter half of Ivan's reign, whole towns were destroyed. It was in effect a civil war, except with no resistance.