The Kronstadt rebellion took place in the first weeks of March, 1921. Kronstadt was (and is) a naval fortress on an island in the Gulf of Finland. Traditionally, it has served as the base of the Russian Baltic Fleet and to guard the approaches to the city of St. Petersburg (which during the first world war was re-named Petrograd, then later Leningrad, and is now St. Petersburg again) thirty-five miles away.
It is a truism of Leninism that Stalinism has nothing to do with the ideas of Bolshevism. Moreover, most are at pains to stress that these ideas have no relation to the actual practice of the Bolshevik Party after the October Revolution. To re-quote one Leninist: