In the year 1000, Holy Roman Emperor Otto III ventured to Gniezno, the capital of the emerging Polish state, to pay homage to the remains of Adalbert, a bishop and missionary recently martyred by the pagan Prussians he was attempting to convert. While there, Otto forged a partnership with Polish ruler Bolesław Chrobry and oversaw the creation of the Archdiocese of Gniezno.

The emperor's motives have long been a source of speculation, for the creation of the archdiocese did not serve the empire's longstanding interest in exerting influence over its eastern neighbor. On the contrary, it strengthened Bolesław's hand and facilitated Poland's emergence as an independent state. In The Gniezno Summit, Roman Michałowski attempts to illuminate the assumptions and intentions behind Otto's actions. To compensate for the lack of sources concerning the events in Gniezno in 1000, he expands his focus to include related events across Europe in the early Middle Ages.

Michałowski unfolds his argument in three chapters. Chapter 1 explores the processes and politics that surrounded the erection of dioceses in the early Middle Ages. He highlights the factors that determined the prestige of dioceses, including a track record of missionary success among pagans. This made ecclesiastical control of the emerging Polish state, which was adjacent to areas of pagan settlement, especially attractive to neighboring archdioceses like Magdeburg and Mainz.

Chapter 2 focuses on the foundation of the Archdiocese of Gniezno. Michałowski rejects Johannes Fried's thesis that Otto originally had hoped to found a new archdiocese in Prague. The emperor granted this privilege to Gniezno, the author argues, on account of Adalbert's pioneering missionary work and martyrdom, which lent him a kind of apostolic status by early medieval standards. Otto's boundless esteem for Adalbert can be seen in the shrine in his honor that the emperor erected in Rome, the city of apostles. The Archdiocese of Gniezno constituted a gift to the saint, and the emperor hoped to gain in return Adalbert's support in Otto's personal quest for salvation, the success of his missionary outreach, and the prosperity of his subjects. The new archdiocese enhanced the stature of Bolesław, whom the emperor recognized as an ally in the work of spreading the Gospel.

Chapter 3 probes the mind of Otto III (r. 996–1002), the primary architect of the Archdiocese of Gniezno, focusing in particular on three issues: his program of Renovatio Imperii Romanorum, his understanding of the religious dimensions of his imperial office, and his predilection for penance and self-mortification. Michałowski portrays a ruler torn between competing influences. Early in his reign, and in keeping with a more optimistic strain of thought within the imperial Church, Otto committed himself to restoring some of the finest features of the old Roman Empire and to promoting Christianity, processes he perceived as both achievable and complementary. In the final years of his life, spurred on perhaps by Adalbert's example, he focused increasingly on his religious duties as emperor and grew more pessimistic about human nature in general and his own ability to resist the temptations that accompany power. He even contemplated abdicating his office and joining a monastery. His internal conflicts influenced his decision to found the Archdiocese of Gniezno. In making this decision, Otto “sacrificed for Christ the traditions of the Carolingian and Ottonian political thought as well as the interests of the German kingdom” (327), convinced that it would advance the Church's expansion.

The unwieldy length of the book's three main chapters and the many tangents the author pursues makes it easy to lose sight of his central arguments. The patient reader is ultimately rewarded with a fascinating exploration of politics, church-state relations, and piety in the early Middle Ages. While its title suggests a rather tight focus on a particular moment in Polish history, in fact the book encompasses the Frankish and Saxon worlds of the ninth and tenth centuries, with occasional forays further afield and further back in time. This makes good sense, for the early history of Poland's ecclesiastical development was firmly rooted in larger European conventions and processes. Michałowski builds his arguments on a truly impressive array of early medieval texts, complemented with considerations of other artifacts such as artworks, churches, and seals. He presents lengthy excerpts of his written sources in Latin (usually, but not always, accompanied with English translations), and his interpretations are consistently reasonable and judicious. The book deserves a broad readership not only among scholars of Poland's medieval history but medievalists in general.