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
G‑d is always with the oppressed. Even if the oppressor is righteous and the oppressed is wicked, our sages tell us, G‑d is with the oppressed. (Lev. Rabba 27:5)
Visit the prisoners and bring them some happiness. Even if they are guilty; even if, in your eyes, they deserve whatever misery they have. Sit with them, as one of them. Treat them with respect. Bring them joy, and you will find joy there with them.
In that uplifted spirit you will bring them, they will feel human again. They will begin to feel that, if they will only so desire, they could live as a human being was meant to live, in the image of their Maker.
And then there will no longer be any need for the walls of this prison.