Warfare had to be re-propagandised in the 20th Century, particularly in the western world, as a moral crusade. Mass democracy determined that leaders needed to present war as a manichean struggle between freedom and tyranny. The end of the Tsarist regime and the intervention of a liberal American president in the First World War was an ideal opportunity to re-invent conflict as moral crusade in the defence of freedom. The arguments that British, American and other NATONATO nato The North Atlantic Treaty Organisation, the military alliance of Western democracies founded in April 1949 to provide collective defence against Soviet expansion in Europe. The foundational principle — an attack on one member is an attack on all — created the security architecture that governed European politics for the duration of the Cold War and beyond. NATO was created by the Washington Treaty of 4 April 1949, with twelve founding members: the United States, Canada, the United Kingdom, France, Belgium, the Netherlands, Luxembourg, Denmark, Iceland, Italy, Norway, and Portugal. Article 5 — ‘the Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all’ — was the alliance’s central commitment: a Soviet attack on West Germany would be met by American military response, including nuclear weapons. This extended deterrence — the American ‘nuclear umbrella’ over Western Europe — was the foundation of the alliance’s military credibility, since Europe alone could not balance Soviet conventional forces. NATO’s first enlargement brought Greece and Turkey in 1952 and West Germany in 1955, each controversial for different reasons. The alliance’s military structure placed American commanders in senior positions; SACEUR (Supreme Allied Commander Europe) has always been American. The French withdrawal from NATO’s integrated command structure in 1966 under de Gaulle, protesting American dominance of alliance decision-making, created a division that lasted until France’s return in 2009. The end of the Cold War raised questions about the alliance’s purpose; its expansion eastward — Poland, Czech Republic, Hungary in 1999, then the Baltic states and others — was justified as consolidating the democratic peace but generated the Russian grievance that contributed to the 2022 invasion of Ukraine. NATO’s history raises a fundamental question about the relationship between collective defence and sovereignty. The alliance’s effectiveness — it deterred Soviet military aggression against Western Europe throughout the Cold War — depended on the credibility of the American commitment, which in turn required American control over key decisions including the use of nuclear weapons. Members accepted a degree of sovereignty limitation in exchange for security guarantee; de Gaulle’s France found this trade-off unacceptable; most others found it necessary. The post-Cold War expansion eastward repeats this dynamic in a new context: the Baltic states wanted the security guarantee badly enough to accept the sovereignty constraints it implied; Russia objected to the expansion not because it threatened Russia militarily (NATO has never attacked Russia) but because it represented the consolidation of a security architecture that permanently excluded Russian influence in Eastern Europe. Whether NATO’s expansion was a strategic mistake that provoked Russian aggression or a necessary response to legitimate Eastern European security concerns is one of the central debates of contemporary strategic studies, with genuine arguments on both sides. leaders present in the 21s