Studying in Berlin, Germany in 1929 at the same time with the Lubavitcher Rebbe was Rabbi Joseph B. Soloveichik. Over the years, Rabbi Soloveitchik’s Talmidim heard vignettes of the relationship. Here’s a part of the interview with Rabbi Fabian Schoenfeld, Former President of the Rabbinical Council of America
"...I consider myself, B’chasdey Hashem lucky, that I was able to be with the Rav literally, for over fifty years, just about, until the day of his passing. The Rav was Zt"l was a student at University in Berlin and I think this is where the Rebbe and the Rav met.
"He [Rabbi Soloveicthik] told us, "I remember him [the Lubavitcher Rebbe] from Berlin That he never missed going to the Mikva a single day during the time he was in Berlin." Lets face it, going to Mikva every day is not exactly in the textbooks of the Brisker dynasty, but the Rav was impressed by it; Here’s a young man – university, college, lectures, professors – he was able to separate this. So every morning he went to the Mikva, that’s what the Rav said. I remember his exact words: "I can testify, he never missed going to the Mikva, one single day.""
While studying in university as a student Berlin, Germany the Chabad Lubavitcher Rebbe Rabbi Menachem Mendel Schneerson went to the Mikva every day Also: Mr. Julius Berman & Rabbi Menachem Genack. Moshiach Now