1949年4月下旬,长江防线被突破后,国民党纠集8个军25个师209余万人退据上海。上海位于东海之滨,濒临长江出海处,人口600万,是中国的最大城市和经济中心,又是帝国主义侵华的主要基地,战略地位极为重要。郊区地形平坦,村庄稠密,河流沟渠纵横。守军以水泥地堡为核心,构筑大量集团 In late April 1949, after the breakthrough in the line of defense of the Yangtze River, the Kuomintang mobilized more than 2,090,000 people in 8 divisions and 25 divisions to surrender to Shanghai. Located on the shores of the East Sea, Shanghai is on the verge of a seaward exit of the Yangtze River with a population of 6 million. It is China’s largest city and economic center, and is also the main base for imperialist invasions of China. Its strategic position is of great importance. Suburban flat terrain, dense villages, vertical and horizontal river ditches. Shoujun cement bunker as the core, build a large number of groups