The policy of Appeasement
Hitler’s expansionist aims became clear in 1936 when his forces entered the Rhineland. Two years later, in March 1938, he annexed Austria. At the Munich Conference that September, Neville Chamberlain seemed to have averted war by agreeing that Germany could occupy the Sudetenland, the German-speaking part of Czechoslovakia - this became known as the Munich Agreement.
In Britain, the Munich Agreement was greeted with jubilation. However, Winston Churchill, then estranged from government and one of the few to oppose appeasement of Hitler, described it as ‘an unmitigated disaster’.
Appeasement was popular for several reasons. Chamberlain - and the British people - were desperate to avoid the slaughter of another world war. Britain was overstretched policing its empire and could not afford major rearmament. Its main ally, France, was seriously weakened and, unlike in the First World War, Commonwealth support was not a certainty. Many Britons also sympathised with Germany, which they felt had been treated unfairly following its defeat in 1918.
But, despite his promise of ‘no more territorial demands in Europe’, Hitler was undeterred by appeasement. In March 1939, he violated the Munich Agreement by occupying the rest of Czechoslovakia. Six months later, in September 1939, Germany invaded Poland and Britain was at war.
http://www.iwm.org.uk/history/how-britain-hoped-to-avoid-war-with-germany-in-the-1930s