'Rear guard' in the Bible

The armed men went before the priests who blew the trumpets, and the rear guard came after the ark, while they continued to blow the trumpets.

The seven priests carrying the seven trumpets of rams’ horns before the ark of the Lord went on continually, and blew the trumpets; and the armed men went before them and the rear guard came after the ark of the Lord, while they continued to blow the trumpets.

So they stationed the people, all the army that was on the north side of the city, and its rear guard on the west side of the city, and Joshua spent that night in the midst of the valley.