When did the fall of Hitler begin?

Tough question...  I would point to three incidents that
led to the fall of Hitler.  I guess you could say that the one that came first was the
beginning of his fall.

To me, there are three major points
that lead to Hitler's fall.  They are:

1. The
   failure to win the Battle of Britain.  By not defeating Britain, Hitler allowed Britain
   to remain as a potential haven for enemies and staging ground for an invasion of
   Europe.


2. Invading the Soviet Union.  This took too many
   resources and ended up depleting them without any
   benefits.


3. Declaring war on the US.  Hitler didn't need to
   do this.  When he did, he made an enemy of a country with huge resources.  This ended up
   dooming him.