In "Animal Farm," why does Napolean execute animals and ban singing the Beast of England Song?

Napoleon, like many brutal dictators, executes animals to
keep his subjects under his control. If the other animals see that they face the risk of
death if they rebel or even question Napoleon's rulings...they will most likely not
break the rules. Creating fear is a common tactic for rulers who don't want individuals
to break from the common goal.

Napoleon bans the singing of
"Beasts of England" because that was the song of the last rebellion. It was a song that
reminded the common people that they wanted a world where they had a voice and all of
them were equal.  Now that Napoleon has turned Animal Farm into the same (or worse) kind
of farm that Farmer Jones had...he is afraid that the rebellion song will stir up the
people to rebel against him.