Conflict between the Communists and Nationalists continued in the area of Free China, the most severe example being the New Fourth Army Incident. At the same time, Japanese action against the Communists and Nationalists continued; Chongqing was bombed 268 times, making it the most-bombed city in all of World War II, and, even as late as December 1944, the Japanese Operation Ichigo succeeded in taking control of Guangxi, giving them a continuous railway link between Manchukuo and Southeast Asia. The Japanese also prepared to invade Sichuan in an attempt to destroy the regime in Chongqing and take ultimate control of mainland China; however, they were forced to surrender before this plan had succeeded.