Western betrayal

The concept of Western betrayal refers to the view that Italy, the United Kingdom, and France failed to meet their legal, diplomatic, military and moral obligations with respect to the Czech and Polish nations during the prelude to and aftermath of the Second World War. It also sometimes refers to the treatment of other Central and Eastern Europe nations at the time.

In particular, it refers to Czechoslovakia's treatment during the Munich Agreement and subsequent occupation and partition by Nazi Germany, Hungary (The First Vienna Award), and Poland (Invasion of Zaolzie), as well as the failure of the Western allies to aid Poland upon its invasion by Germany and the USSR in 1939. The same concept also refers to the concessions made by the United States and the United Kingdom to the USSR during the Tehran, Yalta, and Potsdam conferences, to their stance during the Warsaw Uprising, and some other events, which allocated the region to the Soviet sphere of influence and created the Eastern Bloc.

Historically, such views were intertwined with some of the most significant geopolitical events of the 20th century, including the rise and empowerment of the Third Reich (Nazi Germany), the rise of the Soviet Union (USSR) as a dominant superpower with control of large parts of Europe, and various treaties, alliances, and positions taken during and after World War II, and so on into the Cold War.

...
Wikipedia