In this article, the author traces how the lessons of the Munich Agreement of September 1938 (on the basis of which Czechoslovakia was forced to cede the predominantly ethnic-German Sudetenland to Nazi Germany) were projected into US foreign policy. In Part One of the essay, based on published sources and unpublished documents from American archives, the topic is covered from the late 1930s to the outbreak of the Korean War (which is discussed in Part Two, to be published in the next issue of Soudobé dějiny). The author looks at immediate American reaction to the North Korean attack on South Korea in June 1950, and then returns to autumn 1938 to test his hypothesis that behind the unusual unity of this reaction was the ingrained negative attitude of the United States to the policy of appeasement. He demonstrates that since the late 1930s the terms ‘Munich’ and ‘appeasement’ have remained forever linked in US policy and US public discourse, and he discusses the transformations of the perception of the two concepts during the Second World War, after the war, and at the beginning of the Cold War. The lessons of Munich, he argues, have drawn on the idealistic as well as the pragmatic sources of US policy, because they stem from the conviction that appeasement is immoral and does not pay. Whereas in Roosevelt’s policy the general lesson was not to allow Hitler’s expansion, Harry S. Truman, Roosevelt’s successor in the White House, had to use the lessons, despite his own self-restraint, to try to counter the steps of a wartime ally, Stalin’s Soviet Union. The Communist take-over in Czechoslovakia in February 1948 and the blockade of the western sectors of Berlin beginning in the summer of that year were important events on this path.The author further considers the infl uence of this factor on the US approach taken in the Korean War in the early 1950s. He seeks to demonstrate that the decision of the Truman Administration to substantially intervene in this confl ict was a direct consequence of the negative attitude to the policy of appeasing an aggressor. This attitude was also shared by the American public, regardless of party affi liation and political sympathies. Arguments based on the rejection of appeasement, however, soon began to be used by the Republicans as ammunition in the election campaign against the incumbent Democrats and the choice of strategy also became a matter of dispute in the choice of strategy on the Korean battlefi eld after China entered the war. Whereas the White House wished to avoid an unlimited confl ict with China, the Commander-in-Chief of the United Nation Command in Korea, General Douglas MacArthur (1880–1964), was in favour of an uncompromising approach and in fact ceased to obey President Harry S. Truman (1884-1972). After being relieved of his command by Truman, MacArthur became the chief critic of his policies and a hero of Truman’s Republican opponents. In spring 1951, the Republicans organized a special Senate committee hearing on the circumstances of MacArthur’s suspension. The author looks in detail at this exceptional clash in post-war US domestic politics, which was meant to be triumphantly used against MacArthur, but gradually changed into a debacle in consequence of, among other things, the compelling testimonies of Secretary of State Dean Acheson (1893-1971) and Secretary of Defense George C. Marshall (1880-1959). In his conclusion, the author seeks to demonstrate how other US presidents returned to the ‘lessons of Munich’, and he argues that these lessons became Truman’s lasting political legacy and as such became fi rmly rooted in American political discourse. and Přeložil: Jiří Mareš