Board Thread:General Discussion/@comment-29325269-20160825231936/@comment-5308269-20160827013857

The Gorge is not a river by definition of the word "gorge". It's an arm of the sea and it won't freeze over completely enough to allow a horde to walk across it.

Maybe manpower and time is more the issue of than a lack of building materials, but they're never going to build another Wall quick enough.

They can either defend their lands or they can just desert the North. The purpose of a castle is to defend your lands, so this is what the Northerners have to do. Perhaps, instead of just assaulting each settlement and holdfast in turn, the White Walkers just ignore them and march south toward the Neck. From castles like Winterfell, the Northerners could perform hit-and-run attacks on the Walkers and distract their attention.

Moat Cailen is south of Winterfell, the Dreadfort, White Harbor, Karhold, Deepwood Motte and Last Hearth. The Northerners are trying to DEFEND their own homelands AS MUCH as they're preventing the Walkers' advance on the south. If they abandon their keeps, they'll just become homeless refugees at the mercy of their hosts.