“Akiva, grass will grow from your cheeks,” said the talmudic Rabbi Yochanan ben Torta, “and still the messiah will not have come.” A stinging rebuke for the most prominent supporter of Bar Kochba’s would-be messianic leadership of the Jewish people in his 2nd-century rebellion against the Roman oppressors. Who was Bar Kochba, and what did his rebellion signify for Jewish history?