The partitions of Poland in 1772, 1793, and 1795 had an immense impact on various social spheres of the Polish-Lithuanian Commonwealth. While Poland ceased to exist as an independent state, some institutions survived and remained connected to its history and traditions. Religious structures were among the most firmly established. Even in their case, however, the partitions meant the beginning of various transformations. In Disunion within the Union, Larry Wolff contributes to a deeper understanding of this process within the Uniate Church, which had been established in 1595–96 by the Union of Brest. Over the next two centuries, the Uniate Church in the Polish-Lithuanian Commonwealth came to embrace the diocesan structure of seven dioceses with the metropolitan of Kiev, the Basilian monastic order, and almost five million parishioners out of a total population of twelve million in the country.

Split into two parts, the book addresses the interrelated issues of the ecclesiastical organization of the Uniate Church in the context of Polish, Russian, and Austrian politics and Uniate identity in the context of popular piety. The author focuses on the last decades of the eighteenth century in their own historiographical terms and has distanced himself from an anachronistic approach to the history of the Uniate Church that is present in even some very erudite studies published a century ago.

The book provides a useful index and footnotes but lacks a bibliography. The majority of the two hundred footnotes refer to the older and more recent historiography, including Wolff's own extensive research on Vatican diplomacy during the time of partitions and on the history of the Uniate Church. Some eighty footnotes cite archival sources, mostly in their edited and published versions: notably, Acta Sanctae Congregationis de Propaganda Fide; the letters of Iason Smohozhevs'kyi (Jazon Smogorzewski), archbishop of Polatsk (Połock) and later metropolitan of Kiev; and finally, a few instances of edited sources scattered in nineteenth-century editions. Fragments of the documentation of the Warsaw Nunciature are quoted directly from the collections of the Vatican Apostolic Archive. Wolff refers creatively to the works of the older and more recent generations of historians who deal with the history of the Uniate Church (e.g., Edward Likowski and Barbara Skinner). Other authors are quoted to broaden a comparative perspective or give more insight into subtle aspects of religious identity during the time of political transformations (e.g., Jean Delumeau, Jean Fabre, and even Andy Warhol).

The limited use of both archival sources and published studies makes it clear that Wolff's intention was not to offer a thoroughly up-to-date monograph. He does not mention the classic study of Maciej Loret on the Catholic Church in Poland and Catherine II (Kościół katolicki a Katarzyna II, 1772–1784 [Kraków, 1910]), with its extensive description of the Polatsk archbishopric crisis, or the more recent studies of Dorota Wereda; for example, her monograph on the bishops of the eighteenth-century Uniate metropolitanate of Kiev (Biskupi unickiej metropolii kijowskiej w XVIII wieku [Lublin, 2013]) or the collective research on the Basilian Order (Zakon bazyliański na tle mozaiki wyznaniowej i kulturowej Rzeczypospolitej i krajów ościennych [Rzeszów, 2018]). Despite such omissions, the author succeeds in offering a convincing synthesis of the dynamics within the Uniate Church triggered by the partitions of Poland.

A key figure in Wolff's analysis of the situation of the Uniates under Russian Orthodox pressure after the first partition of 1772 is the archbishop of Polatsk, Smohozhevs'kyi. He was critical of Jesuits as the main actors of the Counter Reformation, and he made every effort at the court of St. Petersburg to explain the true identity of the Uniates in front of Catherine II and her Orthodox entourage. His focus was on the correct interpretation of the Union: not as the victory of Roman Catholicism, achieved in Catherine II's words “by various tricks of the Catholic clergy” (83), but as a genuine compromise based on the respect for the Eastern theological and liturgical tradition. The need to strengthen Uniate identity in the context of Orthodox pressure resulted in a more persuasive rejection of the perspective of Latinization, which in fact meant the extinction of the Union, as much as if it had resulted from open persecution. As Wolff rightly points out, “the ‘transit’ to Roman Catholicism” and the “ongoing ‘apostasy’ to Orthodoxy” (85–86) were the two analogous threats to the Union in the post-1772 period in Russia. In the context of the Roman Catholic court of Vienna, the politics of absolute equality between rites contributed to the flourishing of the Uniate Church, renamed the Greek Catholic Church in 1774, which nevertheless felt the impact of the reforming politics of Joseph II. Wolff pays attention to both external and internal tensions surrounding the Uniate Church.

The administrative regulations concerning the Uniates were different but analogous in the case of Russia and Austria. However, they were not the only factors determining the fate of the ecclesiastical body created in the political context of the Polish-Lithuanian Commonwealth, which since 1772 was slowly ceasing to exist. The example of the Basilian monastic order, a stronghold of Latin influences within the Union, led to questions of education, episcopal authority, and relations between the elite and the masses of the faithful. The uneducated parish clergy had the advantage of being close to the people and their popular customs, which surprisingly proved to be the foundation of the post-partitions Uniate identity and perseverance. Wolff's narrative brings together all these various perspectives and provides a thought-provoking synthesis of the history of the Uniate Church during the critical period of the transformation of its status. The changes occurring in Russia, Austria, and Poland had particular institutional contexts, which in some cases threatened the very existence of the Uniate Church. However, the confirmation of the Uniate identity originated from within the Uniate societies and had long-lasting effects.