On May 27, 1949, the Third Field Army liberated Shanghai, the largest city and economic center of China. The Second Field Army assembled on the Zhejiang-Jiangxi Line for combat readiness and rest, ready to cooperate with the Third Field Army to counter the possible armed interference from imperialists. The underground CPC organization of Shanghai has played an important role in cooperating with the People's Liberation Army. On May 30, the CPC Central Committee said in the telegram congratulating Shanghai on its liberation: “People from all walks of life in Shanghai have actively cooperated with our army, which made most of Chiang Kai-shek’s plans fail and restored the order of the whole city quickly. The CPC Central Committee herewith warmly congratulates the PLA on the frontline of Shanghai, the local CPC organizations in Shanghai and all the people of Shanghai.”