Wow, Westeros is Going to Dominate the World Someday

[Max of the Magic Friends]

It occurs to me, looking at the map of the world and weighing everything that we know from the books, that Westeros has an incredible power-base. At the moment, they have all the wealth and resources of an entire continent backing them, united under a single government state. Granted, it is limited by its feudal structure, but history has proven that states that naturally develop out of such a system (like France and Britain, arguably the countries Westeros is most heavily based on) have the capability to be great world powers. 

Meanwhile, the nearby competition is pretty lacking. Oh, it's certainly true that some of the Free Cities are impressive: Braavos has a significant naval and economic power-base, while Volantis apparently has a large population (I recall characters mentioning that their towns are larger than Westerosi cities), but at the same time they and the rest of Essos suffer from incredible disadvantages that will begin to serious hurt over time.

First of all, all our evidence of Essosi population is that the entire continent is supremely underpopulated, thanks to the depredations of the Dothraki riders that have wiped out every city, settlement, and farm from Qohor to the Bones, leading to a great deficit in manpower compared to its size. And even though the Free Cities claim to be the superior people on the Narrow Sea, they have no political unity and no incentive to work together - a death sentence for nations in history when a powerful neighbor becomes imperialistic. Plus, while each of the Free Cities can only use the limited resources immediately available in their smaller and frequently contested territories, Westeros has an abundance of almost every practical resource imaginable: timber, cloth, gold, silver, iron, etc. If they were actually united behind a war effort, they would be able to sustain themselves without any outside help, while the Free Cities would need to hope and pray that they would get support from the others - not at all guaranteed, seeing their historical hatred of one another. Not to mention that many of the Essosi militaries are hideously, hilariously outdated or outgunned, either using hopelessly antiquated units or being reliant on mercenary forces - similar to medieval and Renaissance Italy, they play at wars rather than fight them, as opposed to the seasoned forces of Westeros. Should the west develop professional armies in the near future, there'll be no stopping them.

Even with all this in mind, the Free Cities would still be easily the greatest threat Westeros would face. After the westrons clear them, who can stand in their way? The Summer Islanders are great sailors and archers, but have no interest in the affairs of the continents or taste for total war, and the same can be said for the Ibbenese. Qarth is a merchant city, the Lhazar are pacifists, the Slavers... well, 'incompetent' doesn't begin to cover it. Yi Ti has been impressive in the past, but their glory days are apparently long behind them, being to divided politically. I'm not at all saying that an imperialist Westeros would want to or be able to take over all these places, but there doesn't seem to be any single challenger that can beat them. Despite their pretenses at being more civilized, history has proven that divided, lagging powers like those of Essos are, in time, dominated by their once marginal, backwater neighbors, especially when said neighbors are united together against a fractious foe. Essos is a dead-end militarily, politically, and technologically, doomed to be left behind. 

This is assuming a lot, of course. If Westeros is divided up by the time the series ends, for example, then their future is toast - 7 or more squabbling kingdoms do not have the same potential as a united one. But if it is united, and particularly if it evolves into a more centralized government, then it will be as though colonial Britain started out with the entire landmass of America at their disposal. We could be seeing the first step of a new global empire, one that puts Valyria to shame.

Assuming they ever move past the medieval times, of course...

[shmewdog]

You make a strong argument, but I can't help but notice that you ignored one important aspect.  Attrition.  Once the Westerosi armies cross the Narrow Sea they will be cut off from their source of supply.  This problem will only be exascerbated the farther they conquer into the continent.  Essos is much much larger than Westeros, and the invading army will know little and less of its workings.  The Cities on the coast will certainly face problems, but the rural regions will never truly be conquered.  The Essosi could practice a scorch and burn policy and live off the land while the invaders starve and die, just like what happened to the Germans when they invaded Russia.  Plus the essence of any such army would be the ships, which would be provided mainly from the Iron Islands, the Redwynes and a few scant contributions from other lords.  If Braavos and Volantis combine their fleets then its game over.

[Andorion]

Even if they do defeat the free cities, what of the Dothraki? Incredibly ferocious warriors controlling a huge territory. Even if the Westerosi knights can win in frontal battles because of armour, any campaign inland will be dogged by a hundred Dothraki bands gradually bleeding the column to death. 

And note that armoured knights do not always win against steppe cavalry. The best example is the annihilation of the Hungarian, Polish and other East European knights by the Mongols.

Moreover the subjugation of Essos is a long-term problem and that cannot be achieved in a feudal structure. The feudal levy is a seasonal army which if not released back to the fields would mean no harvest. A serious campaign of conquest would require  a standing army and an absolute monarchy... something like France under the Bourbons. Also I think their best bet lies in the Maesters discovering gunpowder

[Scorpion92]

By the end of the story, big part of Dothraki under Dany will conquer and destroy Free Cities except Braavos, plus I expect Westeros' own population to change ethnically a bit. Besides Dothraki and Unsullied there will be thousands and thousands freed slaves and followers of Red God who believe Dany to be their messiah will follow her across Narrow Sea. First Men and Andals were first two massive people migrations, there needs to be a third one which will happen with Dany at the head.

By the time Westeros unites under a new government (Jon Stark - King and Father, Sansa Stark - Hand of the King and Maiden, Arya Stark - Mistress of Whisperers and Stranger, Sam Tarly - Grand Maester of the new order of the Citadel and Crone, Davos Seaworth - Master of Ships/Admiral and Mother, Gendry - Grand General/Master of Laws and Warrior, Tyrion Lannister - Minister of Finance/Master of Coin and Smith), the whole western Essos will be a pile of ruin and chaos overridden by Dothraki hordes thanks to Dany. One major force remaining might be Braavos, but I doubt they survive Long Night unscathed. 

The path to the Bone Mountains might be open and ripe for taking, especially if Jon will marry Dany, then he can claim her conquered territories as his and go further conquering towards Jhogos Nai, Asshai, etc.