Question

When naval engagements occur they are carried on at such great ____ that the intervention of mist may obscure the contestants from each other?

Answer 1

I believe the answer is: Ranges

In warfare, they use long-distance controlled missiles as the main weapon for naval engagement. This means that victory would be held by the sides who are able to pinpoint the location of the oppostion's naval ships or submarine.
Intervention of mist could make the location seeking process become much more difficult.