During a lecture addressing the Torah perspective on the Holocaust, a Rosh Yeshiva mentioned a letter which Rav Aharon Kotler z"tl wrote telling someone to remain in Europe because the war would blow over. This Rosh Yeshiva said that there are times when our actions as a nation may cause Hashem to remove certain foresight from Gedolei Yisroel.
Where is this concept mentioned?
Gittin 56b seems the clearest example, and I have heard this quoted in regards to the Holocaust. Raban Yochanan ben Zakai, effectively chief rabbi of the Jews, is negotiating with the Roman Emperor Vespasian just outside of Jerusalem, shortly before the Romans attack the city (c. 70 CE):
בעי מינאי מידי דאתן לך אמר ליה תן לי יבנה וחכמיה ושושילתא דרבן גמליאל ואסוותא דמסיין ליה לרבי צדוק קרי עליה רב יוסף ואיתימא רבי עקיבא (ישעיהו מד) משיב חכמים אחור ודעתם יסכל איבעי למימר ליה לשבקינהו הדא זימנא והוא סבר דלמא כולי האי לא עביד והצלה פורתא נמי לא הוי
Vespasian told the rabbi -- ask of me something I can give you. He replied: give me [the Northern city of] Yavneh and is scholars; the lineage of Raban Gamliel; and doctors to heal Rabbi Tzadok.
[Decades later], Rav Yosef -- or some say Rabbi Akiva, commented on this encounter by quoting the verse (Isaiah 44): He pushes the wise aside, and their minds go foolish. He should have asked to leave [Jerusalem] alone that time! [What was RYBZ doing planning a post-Temple Judaism when the Roman leader could have called off the Jerusalem campaign entirely!] RYBZ himself thought that if the Roman was asked for all of that, he would refuse and not even minor relief would occur.
So the Gemara is saying G-d kept Raban Yochanan ben Zakai from logic that could have prevented the Second Temple's destruction; it's not a difficult jump from that to many rabbis' suggestions to stay in Eastern Europe. (I don't see anything about this per se being the nation's fault; once the nation no longer deserved a Temple, the Talmud here is saying G-d allowed the pieces to fall into place.)
