In 1565 Ivan the Terrible formed a private army called the Oprichnina. They were completely loyal to him and they killed anyone suspected of being the Czar's enemy. In 1570 The Oprichniks sacked Novgorod because Ivan believed the Novgorodians were collaborating with his enemies the Poles. The Oprichniks massacred the inhabitants, killing thousands. The Metropolitan of Moscow denounced Ivan's cruelty and as a result he was strangled.
Ivan also devised horrific methods of torturing and killing anyone he suspected of being an enemy. Ivan even killed his own son and heir by hitting him with an iron tipped staff. Ivan finally died in 1584. www.localhistories.org/russia