There's a discussion in the comments to this thread about the Soloveitchik-Twersky Rabad thing.
Someone opined that the Soloveitchik review revealed some bad blood, a grudge or a feud, since it's otherwise difficult to see why S. would choose to write a review (and a harsh one at that) of his brother-in-law T.'s book, thirty five years after it had been published. Similarly, R. JJ Schacter must have had some sort of a grudge against R. Leo Jung, whose pulpit he filled, since he co-wrote a lengthy article called "The 93 Beth Jacob Girls of Cracow: History or Typology?," ( Reverence, Righteousness, and Rahamanut: Essays in Memory of Rabbi Dr. Leo Jung, New York: Jason Aronson, 1992, pp. 93-130).
The story of the "93 Beth Jacob Girls of Cracow," is that 93 Beis Yaakov students and teachers killed themselves, rather than be forced into Nazi brothel. It is based on a letter written by one of the girls, Chaje Feldman. The incident was apparently first publicized in America during WWII by R. Jung himself. R. Schacter makes the case that this specific event did not occur.
In other words, the contention is that the story or legend of the 93 girls is highly associated with R. Jung. Thus, debunking the legend has to mean something deeper, some enmity.
R. Schacter edited this volume in memory of R. Jung, and frankly, I think it's crazy to accuse him of harboring some sort of grudge against R Jung, who he seems to have had a great deal of affection and admiration for.
In any event, this is what was reported in the New York Times on January 8,, 1943:
(Download the entire Times article.)
The text of the letter was translated from Yiddish into Hebrew and appeared in Hadoar 23,12, and an English translation of that letter appeared in the Reconstructionist:
(Download this as well.)