Assault Moat Cailin

[John Suburbs]

I think it's important to note that MC has not been tried in thousands of years, when it was still relatively intact and not half-sunk in the swamp. Also, the armies back then would have been smaller considering they were generally marshalled by small river kings or vale lords. So MC not be all that impervious from the south as Ned thinks.

Also, it depends on how many northmen are garrisoned at MC, but if it's only the 200 or so archers that Ned says is necessary, then here is how I would do it:

Dispatch of decent-sized force of, say, 5000 men and follow the coast along Iron Man's bay north of the Cape of Eagles. (I'm assuming that since only the north is in rebellion, then both the Twins and Seaguard are on JonCon's side.) Then cut northeast through the woodlands to the eastern tip of Saltspear, follow the river due east (or if the crannogs control that, then north a few kliks into the flatlands) so you can swing around to take MC from the north. Or maybe for good measure, send 4000 or so north and take Barrow Hall so they can't attack you from the rear. 1k should be plenty to take MC.

And this is assuming, of course, that the crannogmen confine themselves to the swamps on the eastern side but not the forest in the west. If they control both regions, then this would never work.

But it's also inconceivable that JC would control everything but the north and not have a navy to simply ferry his men across the Bite or around Blazewater Bay. Heck, the ironmen would be happy to oblige if his intent is to subdue the north.

[Azai]

A tiny bit off topic. But who currently "owns" or rules Moat Cailin? Is it the Reeds?

And a little more on topic. I don't believe you can look at Moat Cailin alone as the factor it cuts off the south. The Crannogmen are a HUGE factor in this gamble. That before you even have to deal with the ruins of Moat Cailin you have been bled by them and the terrain. Disease, poison, supplies being disrupted, hostile flora and fauna, etc. (Others have echoed this).  But additionally whenever you try to take the time to build things and gather supplies you are meet with the harsh terrain and the Crannogmen doing hit and run. And all the time you take trying to fix problem A and then problem B pops up you have already run out of supplies (Or at least have less than those you are trying to siege)