History
Would you believe that this gentleman was the author of a dissertation titled "Essay to Contribute to the Logical Teaching of the Truth in General and of Scientific Truth in Particular"?
Yes! The man pictured is Rabbi Simon Yisrael Posner, known in America as the Shoproner Rav. He was born in Germany and in the tradition of the time received a solid, well-rounded education in the German public school, known as the "gymnasium" after which he enrolled in the Frankfurt University in pursuit of a doctorate of philosophy.
So what happened?
Well, it isn't exactly clear what drove this revolutionary change of direction in his life but it seems to have had something to do with World War I. Many European Jews were displaced in the course of the war, which triggered a new orientation in life. Traditional Eastern European Jews, upon relocation to the West were likely to become more amenable to enlightenment ideals and professional careers. In the case of R. Posen the reverse seems to have transpired. Upon his exposure to traditional Talmudic Judaism in the east (he may have served in the German army?) he fell in love with it and never looked back. He burned his dissertation, became a Rabbi in Shopron, survived WWII, emigrated to the United States and emerged as as a stalwart of Ultra-orthodox Judaism in the newly transplanted system in America.
In America he could be counted on among a bevy of staunch guardians of the faith. He did not yield an inch in the struggle to convince survivors of the war that America is no different than Europe with regard to religion; all the laws and customs that applied in Europe sill applied in America. Other Hasidic or Ashkenazic leaders --who invariably converted to Hasidism in due time-- included the sharmasher rav, the kasho rav, the tzelemer rav, the krasna rav and the papa rav. All those rabbanim were talented in their own right; they earned their stripes through scholastic distinction and leadership acumen (unlike contemporary Hasidic Rabbis, who assume the mantle through dynastic succession). Moreover, they were all more or less subservient to the paragon of hidebound clinging to tradition by the Hungarian-Hasidic Jewish renewal in America: Rabbi Joel Teitelbaum, the Satmar Rebbe.
According to the blog "On This and On That", a Litvish figure once casually remarked that he "saw R. Pozen's doctorate in Giessen, and it was full of apikorsus! (heresy)", which is a sensible assessment. After all, Kant isn't exactly someone a Hasid would quote as a reliable, orthodox source on what constitutes "truth". (hint: God and the bible settle the debate; ain't that simple?).
But what is clear from a macro historical standpoint is that the Shoproner rav he is far from a lone wolf here in the context of estrangement to traditional Judaism. Two other prominent examples are the Boyoner Rebbe and the Stoliner Rebbe. In both dynasties, Hasidim struggled precariously to get their leaders to be as pious as them. There was this disturbing generational gap in the period surrounding WWI during which no sensible educated person, it seemed, would choose the traditional Jewish route if they had any knowledge of the world beyond.
Was it the rise of Nazi Germany in the mid 30's that was primarily responsible for this polar shift in European Jewry?
Bobov is named after the little Polish town where the original Bobov Rebbe, Rav Shlomo Halbershtam founded the sect. He was adescendant of the the Tzanz'e Rav (Baal Divrei Chayim) and modeled his Hasidic style after the Tzanz.
The Two Viznitz's
Satmar is named after a Hungarian town, whereby a thriving Jewish community existed before WWII. Satmar, like most Jewish towns in eastern Europe had several communities. It had a central, official, Orthodox synagogue, a reformed synagogue and a Hasidic synagogue. In the 1920's the reform population was dwindling while the Orthodox and Hasidic populations were growing. In 1929, the Rav of the Orthodox community in Satmar passed away. Some in the community, bent towards the increasingly popular Hasidic style and a strong leader, consented or even preferred to appoint a Hasidic rabbi. When Rabbi Joel Teitelbaum (then Rav in Krooly) was invited for a Shabbas to Satmar, he demonstrated exceptional scholastic achievement and talmudic knowledge, somewhat different than the prevailing image of a Hasid as being more spiritual and less Scholastic. Those in the community who liked him, liked him even more, and his followership grew after several invitations. When it came down to a vote, the then-Krooly Rav won by a narrow margin. This was definitely a promotion, as the Satmar community was larger, more modern and wealthier. In the beginning, some in the community were very suspicious of having a Hasidic Rav, but the new Rav was very keen in dealing with those people in a very subtle and accommodating way, as he strategically won their hearts over.
Lubavitch is somewhat isolated from the other Hasidic groups. Lubavitch started at the town of Lubavitch in Russia about 150 years ago where the Author of the Tanye lived. He founded the Lubavitch school of Chasidus and passed it on to his posterity. Lubavitch was a rather small Chasidus before WWII. Yosef Yitzchak Shneirson, Lubavitch Rebbe at the time, survived the war and made it to the US soon thereafter. He died in 1949 and left no carry on the Chassidus. His son-in-law Menachem Mendel Shneirson was given the task of carrying on with the dynasty. He, unlike other Hasidic Rebbe's, was college educated and very well-read. He adopted a very mystical but independent approach to the concept of Chasidus. He in a sense reinvented it. He claimed to be just interpreting the "Older Rebbe's teachings. Practically speaking, though, he came up with an entire new model. Ultimately Chabad (a synonym to Lubavitch) developed into a very unique Chasidus. 
