What is the significance of the gun's placement at the foot of the flagpole?

From the text:

"Mr. Jones's gun had been found lying in the mud,

and it was known that there was a supply of cartridges in the farmhouse.

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--once on October the

twelfth, the anniversary of the Battle of the Cowshed, and once on

Midsummer Day, the anniversary of the Rebellion."