From March 1938, pro-Nazis in the Sudetenland, a part of Czechoslovakia with a large German population, started pressing for autonomy and closer ties with Germany. Desperate to avert a crisis, Britain and France decided to mediate. However, rather than supporting their ally Czechoslovakia, they agreed to let Germany annex the disputed territories. War had been avoided, but British Prime Minister Neville Chamberlain's claims of "Peace for our time" would soon be disproved.