These two slogans are based on the expansion of Japan's invasion of China and the new changes in domestic class relations, and are put forward to meet the strategic requirements of the CPC Central Committee on establishing an anti-Japanese national United front. The slogan of national defense literature was first put forward by Zhou Yang, the leader of the underground party in Shanghai literary world, and from this, national defense literature movement, national defense drama and national defense poetry activities were carried out. The popular literary slogan of the National Revolutionary War was put forward by Hu Feng after the Central Committee of the Communist Party of China Commissioner Feng Xuefeng went to Shanghai to discuss with Lu Xun and Hu Feng. Because of the criticism of some writers who advocate national defense literature, a debate has been triggered. Lu Xun wrote that these two slogans can coexist, criticizing the closed-door and sectarian mistakes of some left-wing leaders who advocate national defense literature. This is a debate in the left-wing literary and art circles about the establishment of a United front in the literary and art circles under the new situation, which is caused by some ideological differences. New unity was achieved through the debate, which prepared the ideological conditions for the transition to the anti-Japanese literary movement and the establishment of a broad anti-Japanese United front in the literary and art circles.