At its heart, George R.R. Martin’s epic fantasy series, A Song of Ice And Fire — the inspiration for HBO’s excellent Game of Thrones — is a war story. Armies clash endlessly on Westeros, Martin’s continent of Seven Kingdoms. Legions of fans await the battles in Book Five, “A Dance With Dragons,” published on Tuesday.

The military strategy behind the gambits for the Iron Throne, though, is often MIA. Sure, you can marvel at cool swords named Ice or Oathkeeper, and read elegant...