A Russian ambassador, born at St. Petersburg; became in 1806 head of the secret police; came to England in 1873 on a secret mission to arrange the marriage of the Emperor Alexander II.'s daughter with the Duke of Edinburgh; was one of Russia's representatives at the Congress of Berlin (1827-1889). His brother, Count Paul, fought in the Crimean War, helped to liberate the Russian serfs, fought in the Russo-Turkish War, and was governor of Warsaw during 1895-1897; born 1830.