Deuteronomy 20:2

The priest shall approach The Jews say there was a priest anointed for the purpose, whose office, as we may gather from Numbers 31:6, was to blow with the trumpet when they were preparing for battle. And shall speak to the people Probably exhorting them, in the most persuasive manner, to a courageous and undaunted performance of their duty, considering their cause as God's, and relying on his protection and aid.