The history of warfare is global history, and early modernists have embraced this truth with newfound fervor over the past few decades. The resurgent interest in military history, and in the writing of histories that emphasize geopolitical connections as well as their environmental consequences, is as much about understanding the past as it is about responding to the present. We now take it as axiomatic that no local conflict is ever only local. Any conflict—whether in its causes, its ramifications, or both—is part of a larger, interconnected world.For architectural historians, in particular, the sociological and technological emphasis of military history offers much common ground. Issues including logistics, material and personnel organization, competition for natural resources, and technical invention are fodder for explorations of the links between war and the built environment. We can credit the global and ecological turns for knitting architectural and military history ever closer together, but we should also credit the scholars who are committed to probing the evidence. Among them is Mark McDonald, whose new publication not only makes a group of hundreds of printed military maps available to the public but also dares to make a case for why they matter.The French referred to siege warfare as la guerre obsessive, so it feels fair to commend The Print Collection of Cassiano dal Pozzo, II: Architecture, Topography and Military Maps as the work of an obsessive. In this monumental catalogue, McDonald locates early modern architecture within the most expansive field imaginable. This work encompasses urbanism, art, construction, technology, warfare, ecology, and politics within the realm of print scholarship, and does so with aplomb.McDonald takes as his starting point one collector’s collection. The volume is the latest installment in a decades-long collaborative effort to catalogue the drawings and prints owned by Cassiano dal Pozzo (1588–1657), a patron of the arts who served as secretary to Cardinal Francesco Barberini. Even architectural historians usually left cold by patronage studies ignore Cassiano at their peril. To form his Museo Cartaceo, or Paper Museum, of visual material intended to cover all aspects of human knowledge, Cassiano acquired more than ten thousand works on paper. His collecting tastes ranged widely, and he commissioned drawings of subjects from natural history (citrus fruits, fungi) to art history (inscriptions, tombs, mosaics), and from ancient and early modern architecture to urbanism and antiquarianism. Most of the drawings, watercolors, and prints that he acquired now belong to the British Library and to the Royal Library at Windsor Castle: the complete catalogue will stretch to thirty-seven volumes with the publication of its final parts in 2023.1 The volumes on architectural drawings have become indispensable references for historians, and McDonald himself already has catalogued hundreds of the more than three thousand prints with secure connections to Cassiano—no doubt he owned many more.2The “military maps” of the present book’s title actually comprise a heterogeneous group of prints—only some of which are maps—devoted to battles, sieges, fortifications, and armaments, as well as various other types of visual and textual material related to conflict across early modern Europe. These prints, which McDonald examines in depth across hundreds of individual entries, are housed today at Windsor Castle, where curator Martin Clayton and his staff make them accessible to researchers. The prints are organized in rough chronology according to conflict rather than by artist, many of whom cannot be identified. Unlike the more famous collections of drawings by Leonardo, Michelangelo, and Raphael kept at Windsor, the military material today remains relatively unknown to scholars.Military maps exist within a complicated ecosystem of other printed material. Etched and engraved maps were often published in conjunction with letterpress texts describing the depicted events. Cassiano preserved many of these texts, but others exist today only in separate collections, if at all, and McDonald situates each map within a network of related prints. His entries identify rare and singular prints and transcribe their annotations. Each discrete item also has its place within an overriding narrative of enduring conflict—the territorial wars between the Ottomans and Habsburgs, for example, or the internecine violence of the Thirty Years’ War. Subplots abound.Take the siege of Pontelagoscuro, which began in 1643 as part of the First War of Castro (nos. 3128–36). A sweeping depiction of the siege, published by Giacomo Monti and composed of eight prints on eight sheets of paper together spanning 1.35 meters, has an etched curtain at its border that suggests it was meant to be displayed on a wall.3 When hung this way, the print would have simulated a view through a window, a vista onto a bucolic landscape where something has gone awry. On the south bank of the Po River, papal troops led by Francesco Barberini’s brother Antonio hold off attacks against the town of Pontelagoscuro. The troops also occupy the new fortress constructed on the river’s north bank. Venetian troops allied with Odoardo Farnese, the Duke of Parma, attack both sides of the fortress. A letterpress key associated with the view allows readers to follow along with the siege’s events (nos. 3129–31).A siege is a war of attrition: victory is achieved when the enemy’s position becomes hopeless because of a lack of food, water, and supplies. The side that controls the natural resources has the upper hand, as revealed in both the scale and the emphasis of Monti’s print of Pontelagoscuro. The contest between the two sides is only partly a matter of artillery and fortification. Most of what the viewer sees in this print is not conflict but rather land: trees chopped down and fields trampled over are as much a part of the depicted events as the shots fired. The First War of Castro itself began as a feud between families, but it escalated into warfare when Urban VIII, the Barberini pope, in response to the slighting of his nephews Antonio and Francesco, cut off grain shipments to Rome from Castro, territory controlled by the Duke of Parma. The duke’s failure to pay his debts following this agricultural embargo instigated the papal declaration of war. While other prints of the siege of Pontelagoscuro in Cassiano’s collection detail the fortifications, troop encampments, and military maneuvers of the conflict, only Monti’s connects these elements simultaneously to the complex ecological underpinnings of an early modern siege.Architecture, Topography and Military Maps demonstrates McDonald’s particular skill at finding consequential adjacencies within large collections of prints. His meticulously crafted entries on individual items provide essential details with no excess verbiage. Taken together, these entries add up to more than the sum of their parts, as McDonald teases out themes that unify apparently disparate subjects. Adjacency multiplies meaning. The value of this subtle continuity emerges most clearly in the sections on architectural and topographic prints. A series of entries on St. Peter’s Basilica, for instance, collectively make a major contribution to the literature on that notoriously complicated building. Historians of the basilica have mined Cassiano’s collection in the past with productive results, but McDonald introduces some previously unpublished prints, such as a half-plan of Raphael’s first design for the south chapels and aisles, and a plan of Giuliano da Sangallo’s design (nos. 1697 and 1698). An engraved plan of the Confessio after a drawing by Benedetto Drei, printed before 1626 and covered in handwritten notes identifying significant features (no. 1722), is one of several new contributions. Within the Paper Museum, prints of St. Peter’s are distributed among a number of bound volumes, and McDonald explains the origins of individual sheets, most crucially attending to those that once belonged to other suites or books.Cassiano’s concentration on St. Peter’s extended beyond the building fabric, and his collection includes prints of art and ornament from its interior, such as a large print by Antonio Gentili da Faenza (1519–1609), made from seven joined sheets, that shows an extant altarpiece in the Treasury of St. Peter’s (no. 1734). Judging from the number of festival prints in the albums, Cassiano also took a keen interest in the building’s social functions. Prints of St. Peter’s constitute only one node within the collection, albeit the densest. The topographical albums also include prints of ancient and modern architecture across Rome, and extend to Florence, Genoa, and Padua, among other places. Here again, in useful overview essays, McDonald identifies the print series to which sheets once belonged.A great catalogue, one might say, is a work of sublimation. Its story line emerges directly from the material, without any apparent authorial presence: a narrative without a narrator. In his latest contribution to the catalogue of Cassiano’s collection, McDonald achieves this paradoxical feat of self-effacement. Thucydides analyzed the Peloponnesian War in terms of the proximate causes of recent events versus the long-term causes of underlying tensions. So too, McDonald’s work on the architectural prints and military maps that Cassiano owned operates on dual registers. Scholars will surely rely on this volume as the primary citation for a number of rare prints, dipping into its pages as needed. Reading it from cover to cover, however, reveals that McDonald has made an epochal contribution to early modern architectural history.