The definitive “smoking gun” tape in the case for impeaching Richard Nixon didn’t surface until just days before he resigned. But in a way, his fate was sealed the previous summer, when White House staffer Al Butterfield confessed to the Ervin Committee that Nixon had taped his private office conversations in the first place. From there, it would just be a messy year of Nixon backing into a futile, inevitable corner, until that fateful August night. Also historic: The moment Butterfield confirmed the tapes, the Committee performed the largest simultaneous spit-take in Senate history.