Numbers 31:6
“And Moses sent them to the war, a thousand of every tribe, them and Phinehas the son of Eleazar the priest, to the war, with the holy instruments, and the trumpets to blow in his hand.”
Of every tribe a thousand, throughout all the tribes of Israel, shall ye send to the war.
So there were delivered out of the thousands of Israel, a thousand of every tribe, twelve thousand armed for war.
And Moses sent them to the war, a thousand of every tribe, them and Phinehas the son of Eleazar the priest, to the war, with the holy instruments, and the trumpets to blow in his hand.
And they warred against the Midianites, as the Lord commanded Moses; and they slew all the males.
And they slew the kings of Midian, beside the rest of them that were slain; namely, Evi, and Rekem, and Zur, and Hur, and Reba, five kings of Midian: Balaam also the son of Beor they slew with the sword.
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Cross-References
“And the sons of Aaron, the priests, shall blow with the trumpets; and they shall be to you for an ordinance for ever throughout your generations.”
“And if ye go to war in your land against the enemy that oppresseth you, then ye shall blow an alarm with the trumpets; and ye shall be remembered before the Lord your God, and ye shall be saved from your enemies.”
“But they presumed to go up unto the hill top: nevertheless the ark of the covenant of the Lord, and Moses, departed not out of the camp.”
“And, behold, God himself is with us for our captain, and his priests with sounding trumpets to cry alarm against you. O children of Israel, fight ye not against the Lord God of your fathers; for ye shall not prosper.”
“And Uriah said unto David, The ark, and Israel, and Judah, abide in tents; and my lord Joab, and the servants of my lord, are encamped in the open fields; shall I then go into mine house, to eat and to drink, and to lie with my wife? as thou livest, and as thy soul liveth, I will not do this thing.”