The Treaty of Riga of March 1921 did not signify real peace. It was soon followed by the outbreak of a Polish-Soviet cold war, which many a time in the early 1920s threatened to heat up to boiling point. One of the salient fronts on which it was fought was Ukraine and the Ukrainian question. The means by which it was waged - first by Poland, and subsequently, more successfully, by the Soviets - was by attempts to stir up centrifugal tendencies on enemy territory, leading eventually to the splitting up of the neighbouring state along its national seams. Polish-Soviet rivalry over Ukraine had flared up still at the Riga peace conference. In the following years both antagonists struggled to win over the sympathies of Ukrainians living on either side of the frontier River Zbrucz (Zbruch) and dispersed in various émigré centres, and the weapons employed were propaganda, diplomacy, policy on nationalities, economic projects, political subterfuge, and armed irredentism. Jan Jacek Bruski’s book addresses the first, very important phase of this Polish-Soviet tussle.