It is now evident that killing the Night King defeats the Army of the Dead in an instant. So the military tactics require getting Jon Snow and his Companions in close single combat with the Night King. To me the military tactic is obvious — A large deep Phalanx with obsidian tipped spears. As long as they can neutralize the Ice Dragon (dog fight?) the Phalanx should cut through the Army of the Dead to deliver Jon & Company to the Night King. The battle would be decided in a brawl between the Captains & their Companions. Game over.
Another possibility is airmobile assault. Put Jon’s company on one dragon while Dany’s operates as a gunship to clear an LZ close to the Nights King. But again, you have to nail that Ice Dragon first.
Great points. Defeating the ice dragon will be tricky (possibly emotional, I’m guessing, for Danerys). I’m also wondering if there is some sort of armor plating the dragons could wear that would defeat (or at least deflect) those nasty spears that killed the one last night? At any rate, that is going to be one epic battle!!