No Ordinary Ordination

Following the Bar Kochva revolt, the Roman government under Hadrian’s rule issued many harsh decrees against the Jews. One decree in particular dealt with semichah. Up until that point there had been an unbroken chain of semichah (ordination) from a rebbe to his student dating back to Moshe Rabbeinu. Judges without this authentic semichah are powerless to adjudicate certain types of cases.
The institution of semichah irked the Romans. They decreed that any individual who ordains or is ordained will be executed and the entire city that housed the ceremony will be demolished. Realizing that an ordination ceremony might take place in the outskirts of a city, they decreed further that even if a ceremony took place there, the adjacent city would be demolished.
Despite the grave danger, Rabbi Yehuda ben Bava went ahead and ordained the leading elders of the forthcoming generation: Rabbi Yehuda bar Ilai, Rabbi Shimon bar Yochai, Rabbi Meir, Rabbi Yossi ben Chalafta, Rabbi Elazar ben Shamua, and possibly Rabbi Nechemya. The Gemara points out that in fact Rabbi Meir was already ordained by Rabbi Akiva. However, his semichah was not accepted by all because of Rabbi Meir’s youth at the time. (The Maharshah posits that since Rabbi Meir was the only student of Rabbi Akiva to receive semichah directly from him, R’ Yehudah HaNasi compiled the anonymous Mishnayos to reflect his opinions.)