Was he too stupid to understand the nature of the Nazi threat? Or was he too intimidated by Germany? Or was he actually smart and did this to give Britain breathing space to prepare for the inevitable upcoming war? And lastly, could it have been that he secretly agreed with Hitler's views? I have seen all of these things being said or written by various scholars at different times.
The threat of the Nazis were largely underestimated, and there were voices in Britain that felt like Germany 'deserved' some of the early gains appeasement gave the. I wouldn't call him smart either (at least not in this sense), he honestly hoped war could be avoided.
Great Britain was desperately appeasing Germany and Italy primarily to operating from a position of profound weakness.
The British public had trusted to collective security and arbitration. They trusted, in short, to the League of Nations. This had, however, proven a paper tiger, which is all to clear to us in retrospect, but was less than obvious in prospect.
Based on this misguided faith, the British Government, in full accordance with the British people, unilaterally disarmed, matched only by their American cousins across the Atlantic who were to find themselves in a similar boat. This long-term squeeze of military funding lead to serious shortages in categories like tanks, anti-aircraft and fuel cans.
Many people hastily glancing over the situation in the 1930s consider it akin to a tragic play, a descent into a 'dark valley,' and believe that it all could have been arrested by the democracies had they put their foot down.
The reality is quite different. Germany introduced conscription, openly, in 1936, three years before Britain. Before then von Seeckt had been secretly building up reserves of trained soldiers, had been acquiring illegal weapons of war, had been illegally making advances.
Germany was also illegally building an air force, though disguising it as a civilian air fleet. Worse yet, the real gain Hitler made was organizing industry for mass production, as Kennedy (yes, John F Kennedy wrote a thesis on the subject, 'Why England Slept', alluding to Churchill's book 'Arms and the Covenant', called 'When England Slept' in the US) notes it was gearing up for major output rather than actual output.
Churchill noted this when he spoke to the House of Commons and said that his experience of munitions production, as Minister of Munitions during WWI, was that the first year you get nothing, the second year you get little, the third year you get most of what you need, and the fourth year you get more than you want.
When he said this he estimated that Germany was already approaching the end of the third year, while England had not yet begun the second.
The military weakness of the United Kingdom was therefore very profound. There was no question of 'putting its foot down' against the dictators.
In 1935 the Abyssinian Crisis occurred with Italy's invasion of Abyssinia. There was talk of taking a hard line with Italy, but it was found that Egypt was indefensible and that the main guns in the Mediterranean Fleet only had enough rounds for a few salvos.
It was therefore abundantly clear to statesmen in Whitehall that Italy could not be fought. The crisis continued with the outbreak of the Spanish Civil War and the German-Italian-Russian violation of non-intervention agreements and the sinking of numerous vessels, including British-owned and operated, by 'pirates (actually German and Italian submarines though they claimed they had no knowledge of their operation).'
Churchill had, of course, been railing for rearmament for many years already, at least since Hitler got into power. He had been on the whole unsuccessful. Even the crises regarding Italy in the Mediterranean did not serve to shake British complacency, so that England was still a long time in getting into gear.
As a result by the time of Munich in 1938, Germany was in a fairly solid position. Hitler was, naturally, much weaker in 1938 than he was to become in 1939, but people who believe that the Allies should have fought over Czechoslovakia ignore pertinent evidence.
France was strong, to be sure, but the French regarded that the Czechs would be defeated rapidly, and it was clear that however weak Germany was, Britain was infinitely weaker.
The British had, of course, continued to hope that war with Germany could be avoided. But in the meantime Chamberlain's ministry had little choice but to follow appeasement because there was nothing with which England could fight.
Even after the outbreak of war England remained seriously unprepared and in no position to render effective assistance to anybody. This resulted in Poland falling before even the first few British forces crossed the Channel, and the pathetic contribution to the campaign in France and the Low Countries in the summer of 1940.