akuperman, even later than that. First, there was defense against the foreign influences and antagonists. R Salanter explained going from Lita to Paris: you can’t talk to people who are going down the slope, but you can talk to the ones who already landed at the bottom. I think 1967 war was a big source of teshuva movement in USA, including Chabad activities – turning the view of Judaism from a retreating to a more attractive entity.
This kuruv period might be over by now: looking at statistics of Jewish community, I see very little movement from non-O to O at this point. Growth of O is via pru urvu and decline in non-O is due to the lack thereof and assimilation …