On May 12, 1960, archaeologist Yigael Yadin, appearing at the Jerusalem residence of President Yitzhak Ben-Zvi, announced the astounding discovery of a cache of 2,000-year-old letters... signed by the legendary Jewish warrior Shimon Bar Kochba, leader of a devastating second-century revolt against Rome, and had been found high up in a cave overlooking the Nahal Hever canyon, west of the Dead Sea. The news was received with great excitement, both internationally and in a State of Israel that was still searching for connections to the ancient Jewish presence in the land. The Bar Kochba letters, which were supplemented by additional...