The Bellipotent goes out to join a Mediterranean fleet, though, due to its superior sailing quality, it sometimes gets to go out alone as a scout. The narrator acknowledges that there's no reason to tell us this because we're only concerned with the Bellipotent itself, and Billy Budd in particular, but he just can't help himself.
The ship is taking off in the year 1797, which is shortly after the notorious Nore mutiny. A whole fleet of sailors took over their captain's ships, and the event cast fear into the hearts of the higher ups in the British Empire. The point is that it's a scary time to be a captain because all the sailors have the idea of mutiny alive and well in their brains.
British historians tend to sweep this mutiny under the rug. Of course, they can't ignore it out right, so they make passing reference to it, but in general they try to be discreet and confine the Nore mutiny to a place of forgetfulness.
In short, things were pretty tense in the British fleet, but what made them better was that Lord Nelson went south to fight battles at the Nile and at Trafalgar on behalf of the British empire.
Many of the sailors who had taken part in the mutiny went to keep him company, and came back with their navy street cred restored because they took part in the military victory.
The take away is that things are a bit topsy-turvy in the fleet, but at least better than they were right after the Nore mutiny.