Behaloscha

Mei Hashiloach
Before the Aron would leave Moshe would daven and blow the trumpets. Why? Before every trip the Jews would take in the desert there is a large possibility of things that can go wrong, and that Hashem should save them from those disasters.
So why would the trumpets be blown on Yom Tov as well?
Any time there is a change, not just spacial but also in time, there is danger as well. Therefore, the trumpets were blown as a tefillah, that we be saved from it.