If the Greyjoys do attack Oldtown.......?

[The Crow's Eye]

On the whole issue of Victarion/Euron, I think that the horn would have been bound to Euron, but that Moqorro has the potential to seriously screw up his plan. He was betting that Victarion would have no way of knowing how the horn worked or how it could be bound. That said, I still hope that Euron gets a dragon, because that would be nonstop entertainment.

On the issue of Oldtown, there is really no way that the Ironborn could take the city, unless Euron pulls some crazy plan out of nowhere that actually works. That is a definite possibility, and hopefully what happens. The Ironborn need a major victory to prove they're more than just talk, and Euron could always use another chance to show off his cunning madness.

[Batman]

I don't think there is any way that the Greyjoys have 20,000 men after their losses in the North, battles with the Tyrells and the Iron Fleet leaving for Essos. Also they are likely to take HUGE losses in their impending battle with Garlan and his army. I don't know if Euron would be fool enough to engage him on the mainland but if he does he will lose.

I dont think so either, but I thought the question was what would happen if they did.

The Greyjoys strength is difficult to gauge. Their losses in the North were probably smaller than most would think. They attacked a region that was virtually defensless and when the Northerners started fighting back the majority of the Greyjoys force had gone to the kingsmoot and then to attack the Reach. Moat Cailin had little of their original force and Asha had little of her force.

The reason I find it so difficult to gauge the Greyjoy force is that unlike the rest of the seven kingdoms there are almost no crops to attend to. In other threads there have been arguments that only 1-3% of the men can go to war because the agricultural economy would collapse. The Greyjoys have no crops that need tending, plundering is their main source of income. Who knows?

[Batman]

Simce when can a few rocky and inhospitable islands 1/10 the size of the Crownlands support 20,000-30,000 men?

Since they can take every possible man with them. They dont need to leave people behind to keep their economy from collapsing, this is how they make their money. Their steal and rape and pillage. They are also seriously overpopulated, hence why Asha was trying to secure land in the North.