The schools of Shammai and Hillel for the very first time disagreed regarding a case of Jewish law. This occurred around the turn of the 1st century. In the ensuing generations, the schools argued regarding many different laws, until the law was established according to the teachings of the "House of Hillel" -- with the exception of a few instances. According to tradition, following the arrival of the Moshiach the law will follow the rulings of the House of Shammai.
All throughout, the members of the two schools maintained friendly relations with each other.
After a 12-day sea voyage, the previous Lubavitcher Rebbe, Rabbi Yosef Yitzchak Schneersohn (1880-1950), disembarked at the New York harbor on the 9th of Adar II of 1940, following his miraculous rescue from Nazi-occupied Warsaw.
Links:
Vintage film clip of the Rebbe's arrival in NY, March 19, 1940
More about Rabbi Yosef Yitzchak of Lubavitch
When the Mighty Waters cover your head, suffocating the soul and the flame that burnt inside . . .
When raging torrents of confusion drag you away in their current, ripping you from your hold on Life . . .
Look deeper. Beyond the soul.
For the soul itself, as well as the flame it holds, are rooted in a serene G‑dly World of Emanation, a world of quietness and sublime harmony.
But the turbulence of this world is rooted even beyond that, stemming from a World of Confusion, of light unbounded and untamed, before the orderly emanation of defined being, “and the world was confused and void, with darkness over the face of the deep.”
So you must dig deeper than those roots, to find the coals from which the flame arose and the flint rock from which the spark was struck. Deeper, until you reach the primordial essence of the soul, beyond Emanation, beyond Light—even beyond the unbounded light of pre-creation. Where there is nothing but the seminal thought which inspired all that is and was and will come to be.
And what was that thought? It was the thought of you here and now, in your struggle with this world, and the delicious taste of your victory.
And, since in that thought there is no past and future, there, in that thought, you have already won.
Now you must make it happen.