The Question: Why Didn't Mao Invade Taiwan?

This is a well-written story, but I feel like it was streamlined a bit too much, attributing canceling the invasion to the discovery of Cai Xiaogan's spy ring as the single deciding factor. A similar, yet completely different, single-factor explanation is that a large number of PLA soldiers learning to swim in preparation of an amphibious assault ended up infected with Schistosomiasis, because the Schistosoma japonicum parasite is endemic to China's coastal rivers. https://www.discovermagazine.com/health/the-fluke-that-thwar...

I was also a bit surprised by one big omission in the introduction of Cai Xiaogan:

> In the 1920s, he left Taiwan as a teenager to attend school in Shanghai. On campus, far from home, Cai was apparently lonely and confused, making him easy prey for communist recruiting efforts.

In 1927, hundreds or thousands (depending on the source) of dissidents were killed in the Shanghai massacre, even though Kuomintang and Communists were theoretically allied. https://en.wikipedia.org/wiki/Shanghai_massacre Nowadays, killing dissidents would be more expected of the Communist Party, but back then, they were the victims. If Cai was in Shanghai at the time, witnessing the KMT's violent suppression of their political enemies likely contributed greatly to his decision to join the CCP and eventually lead their espionage efforts in his native Taiwan.