The New Fourth Army Incident occurred during the Sino-Japanese War (1937-1945), during which the Chinese Civil War was in theory suspended, uniting the Communists and Nationalists against the Japanese. It is significant as the end of real cooperation between the nationalists and communists. The Second Sino-Japanese War was a major invasion of eastern China by Japan preceding and during World War II. It ended with the surrender of Japan in 1945. ... The Chinese Civil War was a conflict in China between the Kuomintang (the Nationalist Party; KMT) and the Communist Party of China (CPC). ...

Today, Taiwanese and Chinese historians view the New Fourth Army Incident differently. For the Taiwanese it is an example of communist treachery, for the Chinese it is an example of nationalist treachery.

In the fall of 1940, when the communist New Fourth Army attacked nationalist forces under Han Deqin. Benton's book New Fourth Army argues the communist attack was a counterattack, a response to an initial attack by Han Deqin, and that this initial attack was the result of Chen Yi's goading and harassment of nationalist forces. Regardless, the conflict led to heavy losses for the nationalists. Chen Yi (陳儀 pinyin: Ch ; Wade-Giles: Chen I; 1883 - June 18, 1950) was the Chief Executive and Garrison Commander (警備總司令) of Taiwan Province after it was handed over to the Republic of China in 1945 from Japan. ...

For Chinese historians the incident began in December, 1940, when Chiang Kai-shek demanded the withdrawal of the New Fourth Army from Anhui and Jiangsu. The New Fourth Army commanders complied, but even so they were ambushed by nationalist troops on January 7, 1941, leading to heavy losses in fighting that lasted until January 13. Ye Ting was detained and Xiang Ying killed. Chiang Kai-shek ordered the New Fourth Army disbanded on January 17. However, on January 20, the Chinese Communist Party in Yan'an ordered the reorganization of the army. Chen Yi was the new army commander. Liu Shaoqi was the political commissar. The new headquarters was in Jiangsu, which was the general headquarters for the New Fourth Army and the Eighth Route Army. Together, they comprised seven divisions and one independent brigade, totalling over ninety thousand troops. Chiang Kai-shek ( October 31, 1887 – April 5, 1975) was a Chinese military and political leader who assumed the leadership of the Kuomintang (KMT) after the death of Sun Yat-sen in 1925. ... The New Fourth Army (新四軍 Pinyin: xin-si-jun) and the Eighth Route Army were the two main communist forces from 1938. ... Anhui (Chinese: 安徽; pinyin: Ānhuī; Wade-Giles: An-hui; Postal System Pinyin: Ngan-hui, Anhwei or An-hwei) is a province of the Peoples Republic of China. ... Jiangsu (Simplified Chinese: 江苏; Traditional Chinese: 江蘇; pinyin: Jiāngsū; Wade-Giles: Chiang-su; Postal System Pinyin: Kiangsu) is a province of the Peoples Republic of China, located along the east coast of the country. ... Ye Ting (葉挺); (Sept 10, 1896-April 8, 1946), born in Guangdong Province, was a Chinese military leader. ... Yanan ( Chinese: 延安; pinyin: ; Wade-Giles: Yen-an), is a city in Shaanxi province, China. ... Chen Yi (陳毅, Pinyin: Chén Yì; August 26, 1901 - June 6, 1972) was a Chinese communist military commander and politician. ... Liú Shàoqí (Simplified Chinese: 刘少奇 Traditional Chinese: 劉少奇 Wade-Giles: Liu Shao-chi) (November 24, 1898 – November 12, 1969) was a leader of the Communist Party of China (CPC) and the Peoples Republic of China. ... The Eighth Route Army (八路軍 Pinyin: bālù-jūn) was one of the main military forces of the Communist Party of China, active during the Chinese Civil War and Sino-Japanese War (1937-1945). ...

The New Fourth Army, the Eighth Route Army, and other troops led by the CCP were incorporated into the People's Liberation Army in June, 1946. The Peoples Liberation Army (PLA) (Traditional Chinese: 人民解放軍, Simplified Chinese: 人民解放军, pinyin: Rénmín Jiěfàng Jūn), which includes an army, navy, air force, and strategic nuclear forces, serves as the military of the Peoples Republic of China (PRC). ...