Sunday July 20, 1941. Broadcating V for Victory, writing Stalin.

Churchill's "V for Victory" speech was broadcast by radio, including of course to occupied Europe.

Indian soldier giving the "V for Victory" symbol.

On the same day, Churchill replied to Stalin's letter requesting a "second front" (which ignored the fact that the British were fighting on the ground in North Africa) by informing Stalin that the United Kingdom lacked the ability to do that on the European mainland at that time.  The letter pointed out all that the UK was then doing, and that it would expand its naval efforts northwards to protect sea lanes to the Soviet Union.

Churchill was rather blunt, if polite, in his reply, which actually risked insulting Stalin given as it suggested that Stalin might be quite ignorant of the actual situation faced by the UK, and for that matter, the USSR.

The head of the Russian Orthodox Church in Moscow delivered a radio address in support of Soviet resistance against the invading Germans.  You can read about that here:

Today in World War II History—July 20, 1941

This is actually a fairly complicated story, as the canonical status of the head of the Russian Orthodox Church at the time is a difficult one to easily define. The Church was extremely heavily repressed in this period and a large number of its bishops were not at liberty.  It had in recent years tried to make it plain that it would not interfere in civil government, but that had not brought it relief.  Additionally, its relationship to the church in exile was confusing and would not be sorted out until the fall of the Soviet Union.  Stalin, realizing that adherence, if clandestine adherence, to the Church remained strong, would ease up on its repression during the war, something that more or less started on this day in 1941.