The silver trumpets

Numbers 10:1-10
The silver trumpets
When both are sounded, the whole community is to assemble before you at the entrance to the tent of meeting.
If only one is sounded, the leaders—the heads of the clans of Israel—are to assemble before you.
 When a trumpet blast is sounded, the tribes camping on the east are to set out.
At the sounding of a second blast, the camps on the south are to set out.
To gather the assembly, blow the trumpets, but not with the signal for setting out.
The sons of Aaron, the priests, are to blow the trumpets. 
When you go into battle in your own land against an enemy who is oppressing you. Also at your times of rejoicing—your appointed festivals and New Moon feasts—you are to sound the trumpets over your burnt offerings and fellowship offerings, Then you will be remembered by the Lord your God and rescued from your enemies. they will be a memorial for you before your God. I am the Lord your God.
Two special silver trumpets sounded the alarm, summoned the assembly, and announced the feasts and new months. Long trumpets like these were common in Egypt about 1400-1300BC. Some were buried with the Pharaoh Tutankhamun.
Why?
To million Israelite Moses needs trumpet to let people know where to go and what happened to guide the population.
More important is let people remember that the Lord is their God and rescued from their enemies.
God taught Moses how to lead his people in different tools.
How?
To be a leader needs some tools and wisdom, God is the sources of wisdom.