Rabbi Grylak (Mishpacha Magazine (Jan 21, 2013)) defends Chareidi exemption from the army because they are providing greater protection through their Torah learning. He tells the following unbelievable story to support his thesis.
As I write, I recall a story I heard from talmidim of the Chazon Ish some forty-five years ago, when I was collecting material for the biography Pe’er HaDor: the Chazon Ish was irate over the fact that, in order to spare him pain, his talmidim and family hid the facts from him about what was happening to the Jews of Europe under the Nazi reign of terror. When he learned the true extent of the disaster he blamed them for not informing him. His brother-in-law, Rav Shmuel Greineman, quotes him in his book on the Chafetz Chaim as saying that had he known, “Men nit gelozt” (We wouldn’t have let it happen).
What exactly the Chazon Ish meant by this remark, I cannot presume to say. But at the least, it indicates the strength of the Jewish belief in what Torah study can effect in this world.
Note the following assertions 1) Chazon Ish did not know what was happening in Europe during the Holocaust. 2) He didn't know because he was shielded from information which was common knowledge by his family and students 3) Furthermore he was upset when he found out the truth - not because he was shielded - but because he apparently could have stopped the Holocaust had he been aware of it!
This is shows the power of Torah learning!?