To make a sudden attack (e.g. on an enemy from a defended position).
A feeding strategy of some birds is to sally out from a perch to snatch an insect and then returning to the same or a different perch.
To set out on an excursion; venture; depart (often followed by "forth.")
As she sallied forth from her boudoir, you would never have guessed how quickly she could strip for action. - William Manchester
To venture off the beaten path.
The act of one who sallies.