World War II communists launched an offensive in Central China; in retaliation, Japan instituted harsh measures in occupied areas to reduce human and material resources for the communists. Continued antipathy between Chinese communist and nationalist forces culminated in armed clashes in January 1941, effectively ending their co-operation. In March, the Japanese 11th army attacked the headquarters of the Chinese 19th army but was repulsed during Battle of Shanggao. In September, Japan attempted to take the city of Changsha again and clashed with Chinese nationalist forces. German successes in Europe encouraged Japan to increase pressure on European governments in Southeast Asia. The Dutch government
Declarations of war during World War II 1907 (or Hague II). For the diplomatic maneuvering behind these events, which led to hostilities between nations during World War II, see the article entitled Diplomatic history of World War II. Below is a table showing the outbreak of wars between nations which occurred during World War II. Indicated are the dates (during the immediate build-up to, or during the course of, World War II), from which a "de facto" state of war existed between nations. The table shows both the "Initiator Nation(s)" and the nation at which the aggression was aimed, or "Targeted Nation(s)". Events listed include those in