1. Exposition

What would blowing the trumpet signal?

Judges 3:27 (ESV)

27 When he arrived, he sounded the trumpet in the hill country of Ephraim. Then the people of Israel went down with him from the hill country, and he was their leader.

That would have signalled to all who heard that something dramatic had happened: the left-handed son of the tribe of the son of the right hand had achieved his goal! He has dealt definitively with the head of the enemy. And the people regard him as a hero, and acknowledge him as their de facto leader.