 In 1830, the szlachta, began the November Uprising and after its failure, Nicholas I began a systematic policy of cracking down on Polish influence in the lands of modern Belarus that were claimed by Russian tsars as "White Russia".First the ruling class was removed, and the Belarusian Greek Catholic Church, at the Synod of Polotsk reverted to Eastern Orthodoxy under the leadership of Joseph Semashko in 1839.Meanwhile, since the mid-1830s, ethnographic works about Belarus began to appear, the tentative attempts to study the language were taken up (e.g., Belarusian grammar by Shpilevskiy).