There was once an uninhabited islet lying close to the Chinese side of the Ussuri River, which marks the border between Russia and China in the Far East. “Was,” because it has since attached itself to the Chinese bank in a defiant act of geographic irony. But during the turbulent spring of 1969 this little islet — called Damansky in Russian and Zhenbao Dao in Chinese — was the stage for a game-changing encounter.