In the debate over who deserves credit for causing the Berlin Wall to collapse on the night of November 9, 1989, many names come to mind, both great and small.

There was Günter Schabowski, the muddled East German politburo spokesman, who in a live press conference that evening accidentally announced that the country's travel restrictions were to be lifted "immediately." There was Mikhail Gorbachev, who made it clear that the Soviet Union would not violently suppress people power in its satellite states, as it had decades earlier...