Both the motives and outcomes of China’s 1895 war and the 1950 war prove the fallacy of the claim that Taiwan is China’s core interest.
Marxism could not have been not the reason of China’s 1895 war with Japan, and that’s not what I’m implying. Marxism was not introduced into China until the Chinese Communist established a separatist armed rebel regime in 1931 and not formally established until 1949.
However, Marxism was the reason China’s 1950 war with the United States. This is precisely my point.
In both cases, as in numerous other cases in China’s history, Korea was China’s core interest. China suffered great casualty to oppose to Korea’s independence from China. If there’s anybody opposing Korea’s independence, it’s China.
(And you’re wrong about “influence” too. It wasn’t about competition for influence. It was about sovereignty. The Korean did not have sovereignty. Their sovereign legally and practically was the Emperor of Manchu since 1636. )
And you were WRONG about the founding of Republic of China. The Republic of China was founded with the full support of the Japanese Empire. Taiwan was not ROC’s founding principle.