Numbers 10:4
And if they blow but with one trumpet, then the princes, which are heads of the thousands of Israel, shall gather themselves unto thee. And if they blow but with one trumpet, then the princes, which are heads of the thousands of Israel, shall gather themselves unto thee.
A blast on one trumpet alone was the appointed call for the princes, the heads of the thousands of Israel, to gather themselves to Moses. That single sound did not call the whole congregation, but summoned the leaders to assemble before him. The trumpet sounds had distinct, understood meanings that gave definite directions for gathering and for movement. Because each signal was known, the people could follow what was commanded and move in order without confusion of sound.
The sons of Aaron marched near the ark behind Moses and Aaron bearing trumpets, received directions from Moses, and announced them to the people through the trumpets. A special signal first called for attention, and then certain sounds commanded specific movements that the people understood. With each signal the head officer of each company gave definite directions, so there was no confusion of sound. At Sinai the trumpets gave the signal to break camp and leave, and at the sound the entire camp set forward. The tabernacle was carried in the midst, and each tribe marched in its appointed position under its own standard, all watching anxiously for the cloud to show in what direction they should go.
None who gave attention were left ignorant of what to do, for all who heard the distinct signal were expected to understand and obey it. Ignorance was no excuse when all had the same opportunity to learn what the signal required. Failure to learn and obey brought punishment with death, since such ignorance was willing ignorance. This thorough organization proves that God is particular about order and discipline and union of action. He is the same God of order now, and He designs the church to learn order and organization from what He instituted under Moses.