“ And seven priests shall bear seven trumpets of rams' horns before the Ark, and the seventh day you shall surround the city seven times, and the priests will blow with the trumpets.”
Seven was the number of divine completeness among many nations. It was seen by all as a sacred number. Something sevenfold was total. (In Sumerian religious literature seven, along with three, were the only numbers ever used even though they were a highly numerate nation, and it was from Sumer that Abram came). Included in the surrounding of the city was the presence of the Ark. This demonstrated to all that what was to happen would be the activity of YHWH, there invisibly with His troops. The blowing of the trumpets and the silence of the soldiers would draw all eyes to the Ark. We are left to imagine the growing fear and dread in the hearts of the inhabitants.