Chapter 16 focuses on a comprehensive analysis of how the principal negotiators of the victorious powers sought to come to terms with the two most vital and indeed intricately interconnected questions of the entire peacemaking process: the challenge of establishing a new security architecture to stabilise the Atlantic world and make it “safe for democracy”; and the challenge of agreeing on the fundamental terms of the German settlement and how to deal with the pivotal problem of what shape and what status was to have in the postwar order. It reappraises how the protagonists came to forge a hybrid system of collective security that combined the novel guarantees of the League of Nations, temporary territorial guarantees, far-reaching disarmament of the defeated power and, crucially, specific security agreements under which Britain and the United States pledged to come to France’s aid in the case of unprovoked German aggression. And it offers a new interpretation both of the challenges of fortifying these elements into a new international concert system that could effectively secure the fledgling Atlantic peace and of the challenges of negotiating terms of a German settlement that could gain legitimacy not only among the victors but also on the part of the vanquished.