Neville Chamberlain announced “Peace in our time” after meeting with Hitler in 1938.  Britain avoided going to war at that time even though they were obligated by treaty to do so.  Chamberlain certainly overspoke himself, but his meeting was wildly successful.  He went over to negotiate more time and and he got more time.

In 1938 Britain was not ready for a war with Germany.  They could produce the Hurricane, but that was quite inferior to the Me 109 and were still experimenting with the Spitfire.  The Germans would have had no problem establishing air superiority over England, a necessity for an invasion.  The British needed time, badly, and Chamberlain bought them time.  His mission, which WAS appeasement, trading Czechoslovakia for time worked.  The next year the Spitfire was in production, and while continually improved during the war, was ready to take on the Me 109.

In September, 1939, Hitler invaded Poland and Britain and France declared war.  Britain had used the year Chamberlain bought at the expense of their treaty obligation, and appeasing Germany, to become barely ready for that war.  One year earlier and Hitler probably would have prevailed.

Chamberlain did the right thing.  Maybe for the wrong reason, but it was the right thing.  Britain needed more time to develop and produce weapons, especially the Spitfire.