At this point (27 September 1938) U.S. President Franklin D. Roosevelt entered the picture. Urging Hitler to lay the controversy before an international conference, he added: "Should you agree to a solution in this peaceful manner I am convinced that hundreds of millions throughout the world would recognize your action as an outstanding historic service to all humanity."
Roosevelt also joined with Chamberlain and French Premier Édouard Daladier in a plea to the Italian dictator Benito Mussolini to persuade Hitler to accept a peaceful settlement that would give him substantially all he asked for. Hitler yielded to the extent of agreeing to meet with Mussolini and the French and British leaders at Munich. There, on 29 September, Hitler and Mussolini and Chamberlain and Daladier agreed on a plan that the Czech government perforce accepted. It differed little from Hitler's ultimatum of a week before, merely allowing slightly more time for Czech withdrawal from the surrendered area. The American contribution to the crisis was confined to a message from Roosevelt reminding all the European powers concerned of their solemn obligation under the Kellogg-Briand Pact (1928) not to go to war with one another. The Soviet Union was not invited. In any case, it was assumed that war had been averted. Prime Minister Chamberlain told the people of England that he had brought back "peace with honour," adding, "I believe it is peace in our time."
Two Czechoslovak diplomats summoned to Munich were held overnight under Gestapo guard and confronted on the morning of 30 September with what the great powers had done. Prague was forced to give in to the pact's terms. Jan Masaryk, son of the founding father of the Czech Republic, warned Britain and France, "If you have sacrificed my nation to preserve the peace of the world, I will be the first to applaud you. But if not, gentlemen, God help your souls!"
The Wehrmacht was to be allowed to take over the German-speaking frontier area of Czechoslovakia during the first ten days of October with all the military installations it contained. What was left of the republic was to be placed under some kind of indeterminate guarantee, never enacted.
The Munich pact was hailed as a triumph of diplomacy over war, and Chamberlain returned home to a hero's welcome. Nevile Henderson, the British ambassador to Berlin at the time of the conference, later wrote that "it was solely thanks to Mr. Chamberlain's courage and pertinacity that a futile and senseless war was averted." He wrote to his prime minister, saying, "Millions of mothers will be blessing your name tonight for having saved their sons from the horrors of war." The London Times reported that "No conqueror returning from a victory on a battlefield has come home adorned with nobler laurels." Americans greeted the Munich settlement with profound relief that war had been avoided. Thus, the American government and people at this time obviously favored appeasement with Hitler as the alternative to war.
As Hitler violated his pledges and anti-Semitic outrages multiplied in Germany, Roosevelt publicly voiced disapproval. He recalled the American ambassador after the violent Kristallnacht ("night of broken glass" on 9–10 November 1938) in Germany, a wave of anti-Jewish riots and stringent repressive measures that followed the assassination of a German diplomat in Paris by a Jew.
Hitler fully reciprocated American dislike and recalled his ambassador. He viewed the United States as a racial mixture that could not even cope with the economic depression. The United States, with its political weakness and degenerate culture, he told his intimates in 1938, would prove no match for German will. The United States was too impotent to fight and would not go beyond meaningless moral gestures in international affairs. The German military shared his opinion. Using "racial arithmetic," Hitler concluded that the polyglot United States was held together only by the glue of 20 million superior Anglo-Saxons or 60 million of valuable racial stock, therefore Germany, with its larger population of Aryans, was far more powerful. America's neutrality laws in the 1930s merely strengthened his contempt.
The Munich settlement proved to be but the prelude to the complete extinction of Czechoslovakia as an independent nation. Hungary and Poland demanded and received slices of Czech territory where Magyars and Poles were numerous. As a result of the crisis, Hitler annexed to Germany more than 3 million Germans of the Sudeten region. Politically, Hitler's success broke the back of the "Little Entente"(the alliance system of smaller states that sought to preserve the central European status quo as established by the Versailles system), gutted the French alliance system in Eastern Europe, and made the Third Reich easily the dominant power in the continent.
Internal dissension between Czechs and Slovaks in March 1939 afforded Hitler the final pretext for taking control of the destinies of those two ethnic divisions of the former republic. Hitler summoned President Emil Hácha to Berlin and induced him to "place the fate of the Czech people …trustingly in the hands of the Führer," who presumably guaranteed "an autonomous development of its national life corresponding to its peculiarities." On 15 March, Bohemia and Moravia became a German protectorate, which was promptly occupied by German troops. The Czech army offered no resistance. The disappearance of Czechoslovakia demonstrated Hitler's readiness to extend his claims beyond "racial" areas and base them on the Reich's needs for Lebensraum, or "living area."
Hitler had declared at Munich: "This [Sudetenland] is the last territorial claim which I have to make in Europe." His absorption of Czechoslovakia had given the lie to that declaration, and by April 1939 he was pressing Poland for consent to annexation of the free city of Danzig and a sort of German corridor across the Polish corridor to give Germany freer access to East Prussia. By this time even Chamberlain had lost faith in Hitler's promises. He abruptly abandoned appeasement and, with France, gave guarantees of aid against aggression to Poland and later to Romania and to Greece, the latter threatened by Italy's occupation of Albania. Geography would make it difficult to implement these guarantees effectively, but they at least served notice on the Axis powers that further aggression against their small neighbors would mean war with the great western democracies.
On 1 September, German forces, led by mechanized divisions and supported by overwhelming airpower, invaded Poland. Two days later, making good their pledge, Great Britain and France declared war against Hitler's Germany. World War II had at last begun. Appeasement was finished.