The paper studies the presence of Sergei Bernstein at Kharkiv university during two decades, in the turmoil of events that happened in Ukraine in the Great War and its aftermath. The apparent refusal of emigration by the mathematician during the 1920s is examined as well as his successful career, leading to a transfer to Leningrad and Moscow in spite of his rather open opposition to some ideological aspects of the Soviet ideology. Some particularities of the local situation in Kharkiv may have played a rôle in this singular evolution.