Remember that Chasidism arose around 1765 in what is now Ukraine; it's
thrust (oversimplifying greatly) was that even ordinary working people can
worship and be accepted by God if they do so with all their heart -- that
one did not have to be a scholar. This radical notion was very popular
among poor working people who didn't have time to devote to study, and was
strongly opposed by the more conservative elements, whose leader was the
Vilna Gaon (>from Vilnius, Lithuania). This led to considerable antipathy
between the Jewish Russishooks and Litvaks.