Seven is a biblical number representing perfection.
Seven priests led the ark of the covenant, the symbol of God’s presence, at the front of Israel’s forces. This arrangement showed that God himself fought against the town. Israel only needed to march and watch, then shout and watch. Finally, they would easily capture the town after God did the work.
The ram’s horn (Hebrew shofar) could produce different pitches to signal either battle or worship. In battle, the shofar warned troops or people in towns of an enemy’s approach. Or it signaled the call to advance or retreat.