Two so far.
Remember, they have discovered 42 plots against Hitler.
And they didn't have nearly as sophisticated means of communication that time.
Two so far that we know about. The Secret Service doesn't report on attempts that don't make the news because it inspires copycats.
cough cough news media
It's less about the means of communication now as it is an absolute state of surveillance to act upon before things are even in motion.
When you went back in time to prevent Hitler's entry into art school so that you wouldn't have to analyse his overrated aquarrells in art class anymore.
I'm trying to find who they are talking about but coming up empty on Hans Duchtelstein
The joke is that a person named Hans Duchtelstein was the previous timelines "Hitler" and after being successful Hitler just stepped in because fate is inevitable.
Reverse: we time travel and kill Hitler, come to the present and Hans Duchtelstein takes Hitlers place but does the exact same thing.
Fun fact: Hitler's father was called Alois Schicklgruber until he was 40.
A pretty convoluted and sketchy turn of events surrounding a small inheritance lead to him being forced to change his last name to Hitler, 10 years before his son Adolf was born.
It's debatable whether Germans would have been as eager to shout "Heil Schicklgruber".
They would opt to "Heil Führer" or something. There are other ways to refer to someone than their given name but it's a fun fact indeed, thanks for sharing!
He could have changed his name, just like Iossif Vissarionovitch Djougachvili.