During the years leading up to World War 2 which nations initially followed a policy of appeasement?

France and Great Britain. They had been most directly responsible for the Versailles peace treaty of 1919 with Germany after WW 1. Both countries had come to realize that giving away big chunks of Germany to newly established countries and imposing immense 'repair payments' and other demands on Germany had been the cause of many great social and economic problems that in turn had led to the wave of resentment on which Hitler had ridden to power.

Both countries had therefore reason to greatly fear a resumption of the war. France only prepared for defense and in the meantime was not prepared to do anything to provoke Hitler. Britain therefore stood utterly alone - the USA had become firmly isolationist - and knew it simply did not have the army to succesfully face Germany if it would now confront Germany with any form of ultimatum.

British PM Neville Chamberlain has been much maligned for his appeasement policy. But realistically speaking, he had little or no alternatives at the time.