Closely related to my previous question "was-the-cloud-in-the-wilderness-war-proof",
Camping in the wilderness would require forces to guard the camp 24/7. And if the cloud was protecting them, the cloud was canceled with the death of Aharon so the camp remained vulnerable.
However, I don't recall the Torah mentioning the requirement for guarding the camp against foreign attacks.
Is guarding the camp mentioned anywhere and if not, why?