Game Of Thrones Season 7: Did The Night King Really Trap Jon And Dany?

3. Eastwatch Is Not A Strategically Relevant Target

The vision sent to Bran and The Hound is a curious one, because of the confirmation of where the White Army are headed. It basically implies that the Night King has identified Eastwatch as a strategically important target, or a weak point in the Wall's defences - the same logic that prompts Jon to send Tormund there to defend it.

But Eastwatch is not important, it's just useful for telling a lie. With the Wall's magic still in place, Eastwatch would be just as impregnable as the rest of The Wall, so it wouldn't matter that there was no-one there to defend it. The magic trumps all Wildlings with swords. So the Night King would not attack there any more than he'd attack Castle Black.

That specific castle is instead chosen because it implies a means to get around The Wall (which wouldn't work for anyone aware of the defensive magic, but which the Jon might assume is a loophole in the Wall's defence). The white army attacking the end of The Wall with purpose implies urgency, which is precisely why it's so useful - it makes Tyrion's rash plan all the more urgent and more rushed.

The only reason the Night King choses Eastwatch is that it makes the threat seem more immediate, and ensures Jon and his allies are forced into action impulsively - which sets off the collapse of the tower of cards that ends with Dany flying North and the dragon falling into his lap.