Why was Mao able to eventually seize power for a communist regime in China?

Why was Mao able to eventually seize power for a communist regime in China?

Discuss the evolution of China's military from the 20th and 21st Century. Make sure to use sources to discuss your answer.

If you had to select the single most pivotal moment in the last 100 years, what would it be? why? how did you selection impact the course of Chinese history?