The armed warriors from the tribes of Reuben, Gad, and the half-tribe of Manasseh led the Israelites across the Jordan, just as Moses had directed. These armed men—about 40,000 strong—were ready for battle, and the Lord was with them as they crossed over to the plains of Jericho.
Joshua 4:12-13 NLT

These are the men from the tribes who had already been allocated their land on the other side of the Jordan (Joshua 1). They had reached their promised land already. They were fully armed and ready for battle as they led the rest of the people into the promised land.

When I lead people into salvation, into the promised land, I need to be ready for battle too. New Christians aren’t always ready for what the enemy will throw at them. They are often still busy bringing their possessions and their families across with them. I have to be in the vanguard, ready to defend them.