This magisterial new history elucidates a momentous transformation process that changed the world: the struggle to create, for the first time, a modern Atlantic order in the long twentieth century (1860–2020). Placing it in a broader historical and global context, Patrick O. Cohrs reinterprets the Paris Peace Conference of 1919 as the original attempt to supersede the Eurocentric 'world order' of the age of imperialism and found a more legitimate peace system – a system that could not yet be global but had to be essentially transatlantic. Yet he also sheds new light on why, despite remarkable learning-processes, it proved impossible to forge a durable Atlantic peace after a First World War that became the long twentieth century's cathartic catastrophe. In a broader perspective this ground-breaking study shows what a decisive impact this epochal struggle has had not only for modern conceptions of peace, collective security and an integrative, rule-based international order but also for formative ideas of self-determination, liberal-democratic government and the West.

Winner, 2023 PROSE World History Award, Association of American Publishers

'In this opus magnum Patrick Cohrs presents an original and thought-provoking re-appraisal of the transformation of world politics between the era of global imperialism and the aftermath of the First World War. This is a compelling book that should be of interest to anyone who wants to understand how challenging it was to create a stable international order after the 20th century's crucial cataclysm, how the key actors struggled to build a durable peace, and how the consequences of what they thought and did still shape the world of the 21st century.'

Paul W. Schroeder - author of The Transformation of European Politics, 1763–1848

'This ground-breaking work offers a challenging and original interpretation of how and why the international order was transformed at the dawn of a "long" twentieth century. What drove these changes was a struggle, involving an unprecedented number of transnational actors and ideas, to forge rules, norms and institutions of a new Atlantic order among democratic states. The system-building efforts of the post-World War I era were to resonate throughout the entire century.'

Jürgen Osterhammel - author of The Transformation of the World

'An important book that recasts debates about European and global disorder after the First World War in a longer history of Atlantic world-order making since 1860. Advancing the case that the Paris Peace Conference produced an international 'system' that sought to address the question of German power and its place in the world, this new history also offers insights for contemporary debates on the question of China and the prospects for regional and global order in the present disorderly context of the 21st Century.'

Patricia Clavin - author of Securing the World Economy: The Reinvention of the League of Nations, 1920–1946

'Patrick Cohrs's new grand narrative reappraises great-power relations from the late nineteenth century across World War I and the postwar treaties to argue that durably bringing peace to Europe would ultimately require an “Atlantic” system that both reconciled Germany and durably engaged the United States. The reader will find a major reassessment of the peace that might have been and a challenging diagnosis of what sadly prevented it.'

Charles S. Maier - author of Among Empires - American Ascendancy and Its Predecessors

'This is a work of international history par excellence. Patrick Cohrs ambitiously merges an in-depth analysis of international politics with structuralist methods to capture the transformation of global order between 1860 and 1933. The New Atlantic Order offers a convincing structuralist approach to the coming of the Great War, showing that European leaders certainly did not sleepwalk into the abyss. The book's reappraisal of 1914–1918 diplomacy and the Paris Peace Conference, which draws on a massive array of new archival sources, is particularly strong, indeed admirable. Here is an international historian bringing the fruits of his work.'

Paul M. Kennedy - author of The Rise and Fall of the Great Powers

'This magisterial work focuses on the failure to prevent World War II. Cohrs advances [the] argument … [that] any European order [after World War I] based solely on military containment was doomed unless it addressed the deeper sources of all European conflicts from 1850 to the present: diverging claims of national self-determination, opposing economic and financial interests, and intense ideological strife between the political right, left, and center. [The book's] sweeping synthesis and grounding in primary sources makes an impressive thousand-page read.'

Andrew Moravcsik Source: Foreign Affairs

'The New Atlantic Order is an enormous achievement … not just in terms of its sweeping narrative and impressive primary-source base, but also in terms of its innumerable historiographical interventions … (It) … grounds its argument about a transformational ‘long twentieth century’ in a deeper history stretching back to 1860 and extending to 2020 … Cohrs argues that a cohesive 160-year period, … with 1914–1933 as a critical yet incomplete turning point, transformed international order around a Pax Atlantica system, and that this order is now coming to an end.'

Andrew Preston Source: H-Diplo Roundtable

'The goal of [Cohrs'] impressive erudition is … to reconceptualize the entire process of peacemaking [after the First World War] … He sees [it] within three broader contexts, located in temporally ever larger concentric circles. The smallest … involves understanding peacemaking as an attempt to create a 'new Atlantic order', a transatlantic security and economic architecture linking the United States with western and central Europe … [that anticipated] the more successful transatlantic creations after 1945. Surrounding this circle is the broader notion of a 'long twentieth century', running from 1860 to 2020 … The widest circle is a consideration of … international relations from the Congress of Vienna until the present, emphasizing the idea of … a system of co-operation among sovereign states … under the supervision of a power or powers that act as benevolent hegemons. This combination of detailed empirical research and large-scale reconceptualization creates a complex structure with lots of moving parts, impressive to observe in action …'

Jonathan Sperber Source: Times Literary Supplement

'Cohrs goes much further than before (in his new interpretation of the transformation of world order in the long 20th century) … He strongly focuses on the peace settlement after the First World War and here highlights his leitmotif of a new transatlantic order. Yet his approach is always directed at the international order as a whole … (Cohrs argues that) the pre-war era and the Great War would have required a radical transformation of the international system … based on international law and liberal-progressive foundations, reinforced through transnational democratisation processes and pivoted on the League of Nations … A significant scholarly achievement sui generis … (Cohrs' new book is) all in all an admirably tight and comprehensive study.'

Jost Dülffer Source: Historische Zeitschrift

‘Patrick Cohrs, a leading historian of international relations … is … avowedly interested in how principles were applied and institutions developed after the First World War. Yet he also seeks to understand historical complexity and the interplay of power, principle, institutions, and personal ambition. Cohrs … makes a wider argument that modern peace-making following major wars requires the constructive integration of defeated powers. Integration legitimized the making of international order after other systemic wars-the Napoleonic Wars and the Second World War. This integrating process, however, took place... over several years after the end of major war. (He) shows compellingly that by the mid-1920s, the Weimar Republic was integrated into regular, multilateral international negotiations, so that, in this respect at least, peace-making after the First World War looks more akin to other major settlements…'

William Mulligan Source: Society

'Patrick Cohrs has offered … a highly readable and carefully crafted tome, which elaborates upon the oft-told story of the Paris peace negotiations and agreements in 1919 and places them within (a) much broader historical context … One of the great strengths of this volume is the way in which Cohrs has transcended the traditional caesuras of war and revolution to create his own periodization … (He also) goes beyond the traditional diplomatic players of government ministries and leaders to incorporate other voices of civil society, such as non-governmental domestic and internationalist social movements …'

Jennifer Siegel Source: H-Diplo Roundtable

'Arguing that the Paris Peace Conference was a nascent attempt to expand the focus of the international order beyond Europe, Cohrs makes the case in his new book that this was the dawn of a transatlantic order … this is a monumental piece of work … Cohrs' rich empirical work is fantastic, and his interpretation of how conceptions of international order shifted in the early twentieth century is insightful. For students of history and international order, this will prove invaluable.'

Patrick Gill-Tiney Source: International Studies Review

‘… an enormous achievement … not just in terms of its sweeping narrative and impressive primary-source base, but also in terms of its innumerable historiographical interventions…’

Andrew Preston Source: H-Diplo Roundtable

‘… a highly readable and carefully crafted tome … This book is based on masterly archival work ... Cohrs goes beyond the traditional diplomatic players of government ministries and leaders to incorporate other voices of civil society, such as non-governmental domestic and internationalist social movements…’

Jennifer Siegel Source: H-Diplo Roundtable

‘… a feat of intellectual investigation…’

P. Sean Morris Source: International Affairs