Numbers 10:8
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 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.
The blowing of the trumpets belonged to the sons of Aaron, the priests. That appointment was made a lasting ordinance for Israel throughout its generations. In the march the sons of Aaron went just in front of the ark and close to Moses and Aaron, each with a trumpet to receive directions from Moses and relay them to the people.
The trumpets gave distinct, certain sounds that the people knew and understood, telling them when and how to move so that all could act in order. A special signal first called the people to attention, and then commands followed that all were to heed attentively. There was no confusion in the trumpet sounds and therefore no excuse for confusion in movement, and the head officer of each company gave definite directions so that everyone who paid attention knew what to do.
By this arrangement perfect order and thorough discipline were instituted for journeying and camping. The God who established it through Moses is the same God of order now as then, and order and organization are to be learned today from what was then established for Israel.