Japan issues the "Twenty-One Demands" to the Republic of China in a bid to increase its power in East Asia.

The Twenty-One Demands was a set of demands made during the First World War by the Empire of Japan under Prime Minister Ōkuma Shigenobu to the government of the Republic of China on 18 January 1915. The secret demands would greatly extend Japanese control of China. Japan would keep the former German areas it had conquered at the start of World War I in 1914 and would be strong in Manchuria and South Mongolia while having an expanded role in railways. The most extreme demands would give Japan a decisive voice in finance, policing, and government affairs. The last part would make China in effect a protectorate of Japan, and thereby reduce Western influence.

The Republic of China (ROC) began on 1 January 1912 as a sovereign state in mainland China following the 1911 Revolution, which overthrew the Manchu-led Qing dynasty and ended China's imperial history. From 1927, the Kuomintang (KMT) reunified the country and initially ruled it as a one-party state with Nanjing as the national capital. In 1949, the KMT-led government was defeated in the Chinese Civil War and lost control of the mainland to the Chinese Communist Party (CCP). The CCP established the People's Republic of China (PRC) while the ROC was forced to retreat to Taiwan; the ROC retains control over the Taiwan Area, and its political status remains disputed. The ROC is recorded as a founding member of both the League of Nations and the United Nations, and previously held a permanent seat on the United Nations Security Council until 1971, when the PRC took China's seat in the United Nations General Assembly Resolution 2758. It was also a member of the Universal Postal Union and the International Olympic Committee. The ROC claimed 11.4 million km² (4.4 million sq mi) of territory, and its population of 541 million in 1949 made it the most populous country in the world.