The history of the 1930s is relevant to present times in that it demonstrates how extreme nationalism can start in one country and then spread to other countries when democracies fail to exist. Fascist Italy was able to seize Ethiopia in 1935 and evoked no significant response. Hitler's dismemberment of Czechoslovakia in 1938 was met by the appeasement of Munich supported by the argument that the UK was not concerned by such distant lands. Neville Chamberlain was excoriated by history not because his appeasement of Hitler was immoral but because it was mistaken in that he failed to recognize his imperialist ambitions.
Prior to, and following, the Chinese massacre in Tiananmen Square, various Western governments have been accused of pursuing a policy of appeasement with China, dating back in some cases over 20 years since the original seizure of Tibet by China. For example in 1992, President Bush's policy of engagement with China led him to veto legislation which linked the continuation of USA trade benefits to improvements in China's human rights and arms control record. Similarly with respect to the actions of Serbia, notably against Bosnia, the USA and European countries were accused of pursuing a policy of appeasement, and a wheedling diplomacy that rewarded nationalist aggression.
There is certainly no process, politically or military, to recover Bosnian civilians' lost homes, not even on the betrayal terms contemplated by the Vance-Owen plan, finally torpedoed by the very Serbs it so abjectly appeased.
Appeasing Beijing is self-defeating for Hong Kong. Beijing has promised that the social and economic structure of Hong Kong will endure unchanged for at least 50 years. But the Communists made similar promises to businessmen of Shanghai in 1949 – three years before they practically wrecked the city's economy.