
and also the fall of 5000+ years of Dynasty ruling in China. ( 10/10/1911)
It was the Xing Hai Revolution by Sun Yat Sen that topples the corrupted Qing Dynasty and the Republic was formed.
Whatever happens after that was history.
Now you may ask why the fall of Qing Dynasty is the national day of Taiwan.
The KMT, under Sun Yat Sen, was the one who toppled The Qing Dynasty. However, in the 1920s- 1930s, Mao Ze Dong led a large group of farmers and labourers to an uprising against the rich and corrupted politician from the KMT, led by Chiang Kai Shek. The poor supported Mao while the rich ran away.
Hence KMT and Mao fought a civil war until the japanese came. They fought with the Japanese together until 1945.
However, a few years after the end of WW2, Mao and Chiang Kai Shek decided that one needs to rule China.
In the end, Chiang Kai Shek lost the civil war on October 1st 1949 and Mao's Communist party took over China. Mao decided not to pursue further as he was tired also.
Chiang ran to Taiwan and rested there till his death. He ran Taiwan in an autocratic rule under Military law until the early 1990s. All religion and freedom of speech surpressed, not like now where they can make fun of Ah Bian.
In Taiwan, since Sun Yat Sen was the founder of modern China and the leader of KMT, they based on the day 10/10/1911 as the first year of the Republic and its National Day.