Introduction to the Red Army's Western Expedition: The Red Army's Western Expedition was an epoch-making strategic campaign launched by the Central Red Army and the 25th Red Army together with the Northern Shaanxi Red Army after their long march to northern Shaanxi. The victory of the Western Expedition developed and consolidated the revolutionary base areas, and expanded the original northern Shaanxi base area into the Shaanxi-Gansu-Ningxia revolutionary base area. Welcoming the Second and Fourth Front Armies in the Long March, realizing the grand meeting of the three armies, integrating the revolutionary forces, and strengthening the determination of Zhang Xueliang and Yang Hucheng to force Chiang Kai-shek to resist Japan. Only one month after the National Armed Forces Reunion Party on November 12, 1936, the "Xi'an Incident" that shocked the world broke out on December 12, 1936. It promoted the second cooperation between the Kuomintang and the Communist Party, and China entered the period of the National War of Resistance Against Japanese Aggression.