While not perfectly accurate in every respect, it is as near to accurate in all of the important respects: the incredible risks (personal and national) and courage of the Czechs; the importance of Heydrich and his cold, brutal and efficient nature; the ending for all involved, in which no punches are pulled; betrayals and loyalty; how, in military operations, always expect the unexpected. Good understated acting, appropriate to the real people. Portrayal of Heydrich equally understated and disturbingly normal. Great music. Haunting, gut-wrenching ending. Slow build-up to climax finely done. I saw the original in the 1970s; video purchased a few years ago is fine except the subtitles are missing for the short German-speaking parts (which I remember in any case). Key event of WWII: if anyone merited assassination, Heydrich did. Quite apart from his activities in "Bohemia and Moravia" where he was known as the "Butcher of Prague", his top position in the SS and police apparatus (second only to Himmler) and his key role in planning and executing the Holocaust left him with the blood of millions on his hands. Of interest, if you watch Wannseekonferenz (1984; German, with English subtitles) and Operation Daybreak back-to-back, you have a continuous and accurate portrayal of Heydrich's last months. The former covers the 90 minutes of the Wannsee meeting in January 1942 in Berlin in which Heydrich, as second most important police official in the Reich, coordinates the implementation and industrialization of the Final Solution, the latter covers from January to June (his death), in which he has added to his CV by becoming the political administrator of Czechoslovakia (also a likely clue to his future ambitions). The two films could not be more different (one almost a stage play, the other more suspense/action), but are unified by excellent portrayals of Heydrich. It also underlines that while the Czechs assassinated Heydrich for purely national reasons, there was no lack of other justifications. If you cannot obtain Wannseekonferenz, the more recent (2001) English remake (Conspiracy, with Kenneth Branagh) will do. IMDb members rate the German version (8.0) slightly higher than Conspiracy (7.7), a judgement I agree with.
