The Hour Between The Dog And The Wolf

We have had:

The Dog And The Wolf
The Dog And The Wolf

and see also:

Lawfulness And Drunkenness
Safety And Predictability

- but what is meant by "...the hour between the dog and the wolf..."?
-SM Stirling, The Sunrise Lands (New York, 2008), Chapter Seventeen, p. 389.

Stirling's text identifies this hour as sunset. For a book with this title, see here.

The twins, camouflaged and unmoving, demonstrate scouting skills. They spy on enemy scouts but cannot be sure whether those scouts have spotted them. The plot thickens.