Introduction to the main force crossing from the south of the Yangtze River to the north: In June 1940, the Kuomintang army forced the New Fourth Army Jiangnan Headquarters Hospital to move. On June 15, Chen Yi and Su Yu made a strategic plan to cross the river and head north. After learning that the New Fourth Army had moved, the Kuomintang army sent two regiments to pursue and intercept them. In the end, the Kuomintang army was defeated in one fell swoop.