We all got this lesson in history class. Neville Chamberlain went to Munich, and cravenly sold out Czechoslovakia to Hitler. In hindsight, since war inevitably came anyway, it seems that his actions were cowardly.
However, I offer a different view. Chamberlain played the hand he was dealt, and made the only calls he could.
First, it was impossible for the United Kingdom and France to do much of anything to help Prague in case of a war. After the union of Austria and Germany, the western half of the country was surrounded on three sides. France had invested most of its infrastructure into fixed defenses like the ones that got it through World War I, and not tanks and planes. Hungary and Italy's alliances with Germany made it impossible to help Czechoslovakia from the South.
Second, Czechoslovakia itself was a polite fiction. The country was made up of 6 million Czechs, 3 million Germans in the Sudetenland, who really wanted to be part of Germany, and 1.5 million Slovaks who would have preferred independence. There were also large amounts of Hungarians who wanted to be part of Hungary again.
Finally, the united Kingdom wasn't ready for a war. Not yet. They were in the midst of a rearmorment program and the political classes hadn't accepted another war might be needed.
So really, all Neville could do at Munich was keep the peace... because war was an impossible situation.