Prologos, WWI loses for former Czechoslovakia in Great War was 480,000 which were 1/3 of all military loses for entire Austria-Hungary. That was the last major war in which Czech, Slovak, and German population was drafted in battlefield. I use it as a comparision to WWII. Czechoslovakia surrendered to Germany in 1939 without fight, its military loses were 20,000 from armies in exile. The total death toll in WWII was set at 360,000 people which included 240,000 Jews. Prewar Czechoslovakia had 13.6 million. 25% of your estimate would estimate 3.4 million of people, which is not true and impossible. The comparison to Yugoslavia, Poland are irrevelant. Slovakia was a German ally and did not experienced a war until August 28, 1944 when it was attacked by Germany as last country in Europe. Protectorate of Bohemia and Moravia experienced a brutal dictatorship but level of oppression was nowhere close to Eastern Europe. Germans believed that Czechs were Slavicized Germans and intermarriage between these two nations continued through war something impossible in Poland and anywhere east of Protectorate. Lidice massacre is well know and number of executed people were published daily and easy obtainable by census. Another 25,000 died by allied bombing (both of my parents survived air raides) and another 15000 died during combat operations at the end of the WWII in May. 1600-2500 was in Prague alone during last five days known as Prague Uprising. Population loses outside Holocaust was 115,000-135,000. The postwar expulsion affected 2.2 millions of Germans. My grandmother was Austrian German, she was not expelled, lived happily there until she died 90 years old. My father lived in Sudetenland in 1945-1947 where civil war killed in around 18000 people.
Germans and thousands other constantly tries to revive the past injustice in the court. Sudeten Germans after 1939 were not Czech or Slovak citizen, they were German. Even wife of R. Heydrich Lina sued Czechoslovak and British government for killing her husband. Heydrich was a monster, 3rd highest ranking official of 3rd Reich, who initiated holocaust, but was assassinated by Czech undergound in 1942. Her interview is on youtube. Her son continues to sue Czech government for the father's death. Either way I do not know any country in Europe that lost 1/4 of population except Poland. Even Yugoslav losses were established to 1.1 million from postwar guess of 1.7 million from country that had estimated 15 millions before the war.
JW from Germany immigrated to Prague after 1933 and supplied Germany from there. Czechoslovakia was the only democracy there until 1939 where JW could without problem supply Germany. Switzerland played the role as well, but I have seen JW publications before war published both in Czech and German language from Czechoslovakia like The Harp of God. After the war various revolutionary tribunals were set up by people's court to deal with WWII crimes and collaboration, known as a retribution courts. They did accussed JWs in Czechoslovakia for being too docile with Nazis. None of them were proved, and I am not aware that anyone was ever charged and condemned. But these accusations were there. However, during communism JWs did collaborate with the regime and I have seen names of several elders in the list of the informers (their names, address, dob is there so I know who they are). When and If I am in CZ again and I have a time, I can ask courts for records because they are available per request. WWII records should be obtainable too, as well as are postwar summary courts records between 1945-1948 when communist usurped the control.
Breslau or Wroclaw is in Silesia and was part Prussia and Germany from 1742 till 1945. So did Konigsberg. Neither have anything to do with present Czech Republic. In the past there were controlled by Czech Kings is some point like Charles IV or Ottokar II. But this was in medieval times.