I just mean numbers-wise, could the situation between Japan and China ever be comparable to that between England and France in the Hundred Years' War or in other medieval conflicts? It's still sorta mind-boggling to imagine island nations challenging huge mainland states, whether we're talking about the HYW or Japan's invasion of China in WWII.
I'm afraid the scale is not comparable. England's worst ratio was being outnumbered 5:1 by the French. In practice, even that never actually happened, because England controlled other parts of the British Isles and (more importantly) great whopping hunks of France itself. To speak of the HYW as a fight between England and France is convenient, but it would be just as accurate to describe it as a long French civil war between the central government and powerful vassals - one of those vassals happening to have access to English levies.
Japan's best population ratio, to my knowledge was about 9 Chinese to every 1 native son. Which obviously is ignoring the fairly relevant existence of Koreans.
I've been trying to explore this scenario myself just recently. The question is, fundamentally, could the Japanese have achieved the same success as the Jurchens/Manchu.
First of all, where did the Qing Dynasty come from? An organized caste, military, and state system was gradually assembled which could delineate roles in a potential future empire as well as sieze it. A successful peasant rebellion had overthrown the Ming in the wake of climatic problems and government over-spending in defense projects. A Ming general invited in the foreigners to save himself. Then a very long process of conquest began. Conversion to the same faith as the Mongols made it possible to pacify the one great military threat to a state ruling China (before industrial powers navies arrive).
The Japanese could certainly benefit from most of these factors. A resurgent Liao, or even the Qing themselves, could have allowed for wars in northeast Asia that could have expended much of the strength of both China and Korea. If these were quickly followed by large and successful rebellions in China, and Japan had just united as it did under Hideyoshi, it's conceivable that an opportunity would exist.
Let's say we have this much. The Japanese have advantages the Manchu didn't: their heartland is much more secure from external attack, and they also have a larger and more uniform population and military. But they also have severe disadvantages: they can't get their feet wet as the Manchu did (all they can do is jump right in), they're not in a position to coopt the Mongols, and they can't walk to China. The latter is the most critical - they need to control both the Yellow Sea and Korea. Even lacking one would be serious, but if for a moment they lack both, it's all over.
So China concludes a big war to it's north and northwest, or north and northeast, just as Japan is unified. Korea, worn out from its participation in the conflict, is suddenly invaded from the opposite direction. The Chinese are still on campaign far west of there, but they would intervene. Except they can't. One of the peasant rebellions that started during the war (it's interesting trying to find any point in Chinese history when there wasnt a peasant uprising somewhere) snowballs, overrunning much of the Central Plains. That makes it a matter of immediate life or death, and Korea gets nothing.
The Japanese overrun the peninsula fairly quickly, as they did historically, and prepare for a drive through modern Liaoning, planning to march the circumference of the Yellow Sea. That doesn't go as planned. They quickly find that looting Korea is insufficient; if it's to be used as a springboard it must also be administered. Also it would be nice if there weren't guerillas all over the place. The conquerors are not exactly gentle souls, so they probably go a little heavier on the stick than the carrot. Stick here meaning "gun," and carrot "almost enough rice to feed your family." Still and all, with a proper civil war going on across the water, they'll be able to manage.
Then four to six years after they went into Korea the last emperor is dead in Beijing and a Ming general invites them into China. They march into Beijing and proclaim a new dynasty.
I am skeptical that they will ever unify China. They'll probably try to use Mahayana Buddhism and Confucianism as cultural common ground to justify their rule. The former might work well enough in China, but will mean that this Japanese dynasty will never "solve" the Mongol issue as the Qing did in OTL. As for the latter, it's relatively weak sauce in Japan, but it's very Chinese. As a result I expect the dynasty to use it just as the Qing did - over-the-top adherence to the Chinese system to make up for not being Chinese. What that tells me is that we have a state with a hostile populace that is perforce so focused on the security of Korea and the Yellow Sea that it will struggle to meet it's other security goals.
At a guess I would say expansion loses momentum between the Yellow River and Yangtze. The dynasty will have off and on control of the lower Yangtze and southern coast, but anti-Japanese and even pro-Ming states will outlast them. Something like the Revolt of the Feudatories, but never actually ending. There will be regular revolts against the dynasty, but then there were against every Chinese government until Mao. More seriously, the dynasty probably never subdues Mongolia, Tibet, or even northern Manchuria and Xinjiang. Heck, you might even see a restored kingdom of Dali. It's flank will always be open.
We're probably not discussing once of those dynasties that lasts 300 years, is what I'm saying.
Last edited: