Short answers, pulled from the story.
The Chinese Civil War began in 1927 following the Shanghai massacre on the 12th of April 1927. This event turned a political alliance into a bloodbath and marked the beginning of the White Terror and the end of the First United Front.
The Long March lasted over 370 days and covered 12,500 kilometers from 1934 to 1935. Of the 90,000 to 100,000 people who began the march, only 7,000 to 8,000 made it to Shaanxi, where the CCP established a new base.
The Second United Front formed on the 12th of December 1936 after Zhang Xueliang and Yang Hucheng kidnapped Chiang Kai-shek to force a truce with the CCP. This alliance suspended fighting to focus on resisting Japan, though actual cooperation remained minimal during World War II.
The three most significant Communist military campaigns were the Liaoshen Campaign, the Huaihai Campaign, and the Pingjin Campaign. These operations took place between August 1948 and October 1949 and destroyed 144 regular and 29 irregular KMT divisions.
Mao Zedong officially proclaimed the People's Republic of China on the 1st of October 1949 with its capital at Beiping, which was returned to the former name Beijing. Chiang Kai-shek and approximately two million Nationalist soldiers retreated to the island of Taiwan in December 1949.
US President Harry S. Truman ordered the United States Seventh Fleet to sail to the Taiwan Strait in June 1950 as part of a containment policy against potential Communist advance. This action halted the PLA advance towards Taiwan and resulted in a lasting political and military stand-off between the two sides of the Taiwan Strait.