What does Cosimo do when he sees the pirates unloading the boats and what happens as a result of his actions?

Cosimo goes and rouses the townspeople so that they might come and get it before the pirates do. News that the pirates' treasure has been found motivates a sizeable group to gather, and they set off for the cave. Unexpectedly, there is a meeting of pirate chiefs underway at the cave, and so the horn of the sentinels brings them out of the cave, where battle ensues. When the townspeople eventually make a break for the inside of the cave, the pirates decide their best course is to make a run for their boats. Trying to thwart their escape, Cosimo leaps from the trees to the mast of the ship and crosses swords with the pirates until he sees his uncle emerge in a panic from the cave.