Already on the first day of the German attack on Poland the Soviet government, as the secret Nazi papers would later reveal, had rendered the German Luftwaffe a signal service. Very early on that morning the Chief of the General Staff of the Air Force, General Hans Jeschonnek, had rung up the German Embassy in Moscow to say that in order to give his pilots navigational aid in the bombing of Poland—“urgent navigation tests,” he called it—he would appreciate it if the Russian radio station at Minsk would continually identify itself.
