Appeasement
Slovakia separated and created under a puppet government of Germany.
In March 1939, Chamberlain foresaw a possible disarmament conference between himself, Daladier, Hitler, Mussolini and Stalin. British Home Secretary, Samuel Hoare, said, "These five men, working together in Europe and blessed in their efforts by the President of the United States of America, might make themselves eternal benefactors of the human race".
In effect, the British and French had by the Munich negotiations pressured their ally of Czechoslovakia to cede part of its territory to a hostile neighbour in order to preserve peace. Churchill likened the negotiations at Berchtesgarten, Bad Godesberg and Munich to a man demanding £1, then, when it is offered, demanding £2, then when it is refused settling for £1.17s.6d. British leaders committed to the Munich Agreement in spite of their awareness of Hitler's vulnerability at the time. In August 1938, General Ludwig Beck relayed a message to Lord Halifax to explain that most of the German General Staff had prepared a coup against the Fuhrer for if there was "proof that England will fight if Czechoslovakia is attacked". When Chamberlain received the news, he dismissed it out of hand. In September, the British received assurance that the General Staff's offer to launch the coup still stood with key private sector police and army support, even though Beck had resigned his post. Chamberlain ultimately ceded to all of Hitler's demands at Munich because he believed Britain and Nazi Germany were "the two pillars of European peace and buttresses against communism".
Czechoslovakia had a modern well-prepared military, and Hitler, on entering Prague, conceded that a war would have cost Germany much blood but the decision by France and Britain not to defend Czechoslovakia in the event of war and the exclusion from the equation of the Soviet Union, which Chamberlain distrusted, meant that the outcome would have been uncertain. The event forms the main part of what became known as Munich betrayal (Czech: Mnichovská zrada) in Czechoslovakia and the rest of Eastern Europe, as the Czechoslovak view was that Britain and France had pressured it to cede territory to prevent a major war, which would involve Western Europe. The Western view is that the pressure was done to save Czechoslovakia from total annihilation.

German annexation of Lithuania's Klaipėda Region: Rumours had reached the Lithuanian government to the effect that Germany had specific plans to take over Klaipėda. On 12 March 1939, Foreign Minister Juozas Urbšys represented Lithuania at the coronation of Pope Pius XII in Rome. On Urbšys's return to Lithuania, he stopped in Berlin with the hope of clarifying the growing rumours. On 20 March, just five days after the German occupation of Prague, German Foreign Minister Joachim von Ribbentrop agreed to meet Urbšys but not the Lithuanian Ambassador to Berlin, Kazys Škirpa, who was asked to wait in another room. The conversation lasted for about 40 minutes. Ribbentrop demanded the return of Klaipėda to Germany and threatened military action. Urbšys relayed the verbal ultimatum to the Lithuanian government. Because the ultimatum was never set down in writing and did not include a formal deadline, some historians downplay its importance and describe it as a "set of demands", rather than as an ultimatum. However, it was made clear that force would be used should Lithuania resist, and Lithuania was warned not to seek help from other nations. A clear deadline was not given, but Lithuania was told to make a speedy decision and that any clashes or German casualties would inevitably provoke a response from the German military.
Lithuania secretly informed the signatories of the Klaipėda Convention about those demands since technically, Lithuania could not transfer Klaipėda without the signatories' approvals. Italy and Japan supported Germany in the matter, and the United Kingdom and France expressed sympathy for Lithuania but chose not to offer any material assistance and followed a well-publicized policy of appeasement. The British treated the issue in the same way as the earlier Sudeten Crisis and made no plans to assist Lithuania or the other Baltic States if they were attacked by Germany. The Soviets supported Lithuania in principle but did not wish to disrupt their relations with Germany since they were contemplating the German-Soviet Pact. Without any material international support, Lithuania had no choice but to accept the ultimatum. Lithuanian diplomacy characterized the concession as a "necessary evil" to enable Lithuania to preserve its independence, and it maintained the hope that it was merely a temporary retreat.

Outbreak of World War II and Phoney War: By August 1939, Hitler was convinced that the democratic nations would never put up any effective opposition to him. He expressed his contempt for them in a speech that he delivered to his Commanders in Chief: "Our enemies have leaders who are below the average. No personalities. No masters, no men of action.... Our enemies are small fry. I saw them in Munich".
On 1 September 1939, German forces started their invasion of Poland. Britain and France joined the war against Germany but initially averted serious military involvement during the period known as the Phoney War. After the German invasion of Norway, opinion turned against Chamberlain's conduct of the war. He resigned after the Norway Debate in the British House of Commons, and on 10 May 1940 Winston Churchill became Prime Minister. In July, after the Fall of France, when Britain stood almost alone against Germany, Hitler offered peace. Some politicians both inside and outside the government were willing to consider the offer, but Churchill refused to do so. Chamberlain died on 9 November the same year. Churchill delivered a tribute to him in which he said, "Whatever else history may or may not say about these terrible, tremendous years, we can be sure that Neville Chamberlain acted with perfect sincerity according to his lights and strove to the utmost of his capacity and authority, which were powerful, to save the world from the awful, devastating struggle in which we are now engaged".

Attitudes: As the policy of appeasement failed to prevent war, those who advocated it were quickly criticised. Appeasement came to be seen as something to be avoided by those with responsibility for the diplomacy of Britain or any other democratic country. By contrast, the few who stood out against appeasement were seen as "voices in the wilderness whose wise counsels were largely ignored, with almost catastrophic consequences for the nation in 1939–40". More recently, however, historians have questioned the accuracy of that simple distinction between appeasers and anti-appeasers. "Few appeasers were really prepared to seek peace at any price; few, if any, anti-appeasers were prepared for Britain to make a stand against aggression whatever the circumstances and wherever the location in which it occurred".

Avoiding mistakes of First World War: Chamberlain's policy in many respects continued the policies of MacDonald and Baldwin and was popular until the failure of the Munich Agreement to stop Hitler in Czechoslovakia. "Appeasement" had been a respectable term between 1919 and 1937 to signify the pursuit of peace.  Many believed after the First World War that wars were started by mistake, in which case the League of Nations could prevent them; or that they were caused by large-scale armaments, in which case disarmament was the remedy; or that they were caused by national grievances, in which case the grievances should be redressed peacefully.  Many thought that the Versailles Treaty had been unjust, that the German minorities were entitled to self-determination, and that Germany was entitled to equality in armaments.

Government views: Appeasement was accepted by most of those responsible for British foreign policy in the 1930s; by leading journalists and academics; and by members of the British royal family such as King Edward VIII and his successor, George VI. Anti-communism was sometimes acknowledged as a deciding factor, as mass labour unrest resurfaced in Britain, and news of Stalin's bloody purges disturbed the West. A common upper-class slogan was "better Hitlerism than Communism". In France, right-wingers were sometimes accused of believing "Better Hitler than Blum" in reference to the French Socialist Prime Minister Léon Blum at the time. Anti-communism was a motive of a close ally of Chamberlain, Lord Halifax, who said after he had visited Göring and met Hitler in Germany in 1936 and 1937: "Nationalism and Racialism is a powerful force but I can't feel that it's either unnatural or immoral! I cannot myself doubt that these fellows are genuine haters of Communism, etc.! And I daresay if we were in their position we might feel the same!"
Most Conservative MPs were also in favour, but Churchill said that their supporters were divided and in 1936 led a delegation of leading Conservative politicians to express to Baldwin their alarm about the speed of German rearmament and the fact that Britain was falling behind. Baldwin rejected their sense of urgency and declared that he would not get Britain to war with anybody "for the League of Nations or anybody else" and that if there were to be any fighting in Europe, "I should like to see the Bolshies and Nazis doing it".