The appeasement of Adolf Hitler by the British and French governments between 1933 and 1939 is the best-known case of appeasement, and one of the major causes of the negative connotations now attached to the word.
The Munich Agreement in particular stands as a major example of appeasement. There is, however, a large historiographical debate about appeasement.
Reasons the British Government pursued appeasement
Redressing the Treaty of Versailles
The Treaty of Versailles imposed many restrictions on internal German affairs, which the Allied nations later on came to view as unfair to Germany.
Many people argued that German rearmament, the remilitarization of the Rhineland, and the acquisition of the Saarland were merely examples of the Germans taking back what was rightfully theirs.
The Conservative Party gradually began to take this view, in line with popular opinion and Conservative thinking of the time. Many people also believed that since Versailles had created the states of Poland and Czechoslovakia on the basis of self-determination, it was unjust to deny the opportunity of Austrians and Sudetenlanders to join Germany if they so wished.
Because Hitler had not taken any obviously non-German territory as of 1938, a war launched by the Allies at this stage would have been a war launched merely on the basis of suspicion, in which Britain would be deeply divided. This might have proven catastrophic if the war had gone badly for the Allies — as indeed happened in 1940.
By March 1939 Hitler had annexed the very non-German city of Prague — meaning that self-determination could no longer be used to justify his actions. This made a decision to go to war in 1939 far easier than in 1938.
Rearmament
Another major factor in the choice to follow a policy of appeasement was the belief that Britain was not yet capable of fighting a war against Germany. The strength of Nazi Germany was greatly overestimated, while Britain, in recent times, had been following a fairly pacifist policy with regards to its military.
While the policy of appeasement was being followed with Germany, however, Britain began drastically rearming - its military strength increasing far more than Germany’s over the same timescale, due to the greater industrial and economic capacity available to the UK.
Setting Germany against Soviet Union
Conservative politicians not only worried about the threat posed by Hitler's Germany, but also about the threat posed by the Soviet Union. Many British conservatives felt that Bolshevik ideology was a greater danger to Europe and wanted to build up the strength of Germany as a bulwark.
The Chamberlain government in 1937 eventually decided to pursue a more active policy of appeasement to turn Germany eastwards, with the aim of encouraging and allowing Germany to expand towards the east until Germany and the Soviet Union shared a common frontier.
The British government had calculated that this situation of Germany sharing a closer border with the Soviet Union would increase the probability of Hitler launching an attack against the Soviet Union.
This line of thinking proved accurate when Germany invaded the Soviet Union on 22 June 1941.
By setting the Germans against the Bolsheviks, the British government hoped to kill two birds with one stone, expecting that the two enemies would exhaust each another in a German-Soviet war.
This plan to turn Germany eastwards broke down when Hitler insisted on a war against Poland in 1939 and under the pressure of British public opinion, Chamberlain was forced to declare war against Germany.