In Animal Farm, what is significant about the placement of the gun?

The gun represents violence, a tool built for one specific
reason -- to kill. The animals, at first, embrace the commandment in the Laws of
Animalism: "No animal shall kill any other animal." In this spirit, after the Battle of
the Cowshed, the gun is set up as a memorial, symbolizing the defeat of humans by the
animals.

It
was decided to set the gun up at the foot of the Flagstaff, like a piece of artillery,
and to fire it twice a year...
(Orwell, Animal Farm,
msxnet.org)

Later, as
Napoleon takes more and more control over the farm, the gun becomes a propaganda tool,
and it is fired on Napoleon's birthday, at parades, and even when the farmers destroy
the windmill, to trick the animals into thinking that they were actually victorious.
Like other symbols in the story, the gun is used by Napoleon to further his agenda, and
so its initial placement changes from a victory trophy to a symbol of
oppression.