Paul Kennedy defends appeasement, I think very well.
The word is forever associated with Chamberlain and Munich, but I think that is a mistake. As Kennedy explains, the British had done very well over the course of the nineteenth century by making deal after deal and only fighting when they had to. They appeased the US, the Japanese, the French, even the Venezuelans, and only grew more powerful.
Britain's situation of 1940 -- at war with Germany, Italy and Japan, without American or Soviet help -- was pretty much the worst-case scenario. Every player in British politics and diplomacy, including Churchill, thought it should be possible to avoid this situation. Most wanted to buy off or appease somebody to avoid fighting all their enemies at once, or to make every possible concession so that if Britain was attacked, the US would be more likely to intervene. It is easy to criticize British and French actions in retrospect, since the hell they were trying to avoid did come to pass, and when it came they were in a weaker position than they might have been. But who but a lunatic would not have tried to avoid World War II, possibly the greatest disaster in human history?
People need to get over the Hitler thing. Most enemies are not the Nazis, and most of the time diplomacy is better than war.