After the Bar Kokhba revolt the Roman Empire passed a decree that struck at the heart of Jewish continuity: any sage who ordained a student to the rank of rabbi, and any student who accepted such ordination, would be put to death. Rome understood that without semichah, the unbroken chain of rabbinic authority, Jewish law would starve to silence in a generation.
The aged Rabbi Yehudah ben Bava knew the decree and decided to break it in the most complete way possible. He led five students — Rabbi Yehudah, Rabbi Shimon, Rabbi Eleazar ben Shammua, and others whom later tradition (with Rabbi Avaye's addition) named — into a narrow mountain pass between two cities, where no army could operate, and there he ordained them.
Before they could escape, Roman soldiers found the gathering. The old man stood his ground so his students could scatter. He was pierced to death where he stood — three hundred spears, the Talmud says — but the five he had ordained carried the chain of Torah forward. Every rabbi in the world today traces ordination back through them.
Gaster's Exempla of the Rabbis (1924, No. 68) remembers Yehudah ben Bava in a single tight sentence. He died while the empire watched — and the empire did not notice that the thing it was trying to kill had already slipped past it into the future.