The First Sino–Japanese War (Traditional Chinese: 中日甲午戰爭; pinyin: Zhōngrì Jiǎwǔ Zhànzhēng; Japanese: 日清戦争 Romaji: Nisshin Sensō) (1 August 1894 – April 1895) was a war fought between Qing Dynasty China and Meiji Japan over the control of Korea. The Sino-Japanese War would come to symbolize the degeneration and enfeeblement of the Qing Dynasty and demonstrate how successful westernization and modernization had been in Japan since the Meiji RestorationSelf-Strengthening Movement in China. The principal results were a shift in regional dominance in Asia from China to Japan and a fatal blow to the Qing Dynasty and the Chinese classical tradition. These trends would result later in the 1911 Revolution.Japan feared Russian expansion into northern China and Korea, and sought foreign conquests in emulation of the policies of imperialism practiced by its western mentors. Korea’s strategic location opposite the Japanese islands and its natural resources of coal and iron ore also attracted Japan's economic interest. In 1875, Japan imposed the Treaty of Ganghwa on Korea, forced Korea to open itself to Japanese trade and to proclaim its independence from China in its foreign relations. Korea, under the Joseon Dynasty, had traditionally been a tributary state to China's Qing Dynasty. Public opinion in Korea was split, with conservatives wanting to retain the traditional subservient relationship with China, while reformists wanting to establish closer ties with Japan and western nations and to modernize. However, China continued to assert influence over the conservative officials gathered around the royal family. In 1884 a group of pro-Japanese reformers attempted to overthrow the Korean government, but Chinese troops under General Yüan Shih-k'ai rescued the Emperor, killing several Japanese legation guards in the process. War was narrowly avoided between Japan and China by the Sino-Japanese Convention of Tientsin of 1885 the two sides agreed to: (a) pull their expeditionary forces out of Korea simultaneously; (b) not send military instructors for the training of the Korean army; and (c) notify the other side beforehand should one decide to send troops to Korea.

The Second Sino-Japanese War (July 7, 1937–September 9, 1945), also known in Chinese as the War of Resistance Against Japan, was a major war fought between the Republic of China and the Empire of Japan, both before and during World War II. Although the two countries had fought intermittently since 1931, full-scale war started in earnest in 1937 and ended with the surrender of Japan in 1945. The Japanese invasion was a strategic plan made by the Imperial Japanese Army as part of their large-scale plans to control the Asian mainland. Before 1937, the two sides fought smaller engagements in the so-called "incidents." The 1931 invasion of Manchuria by Japan is referred to as the "Mukden Incident". The last of these was the Marco Polo Bridge Incident of 1937, marking the official beginning of full scale war between the two countries. From 1937 to 1941, China fought alone. After the attack on Pearl Harbor, the Second Sino-Japanese War merged into the greater conflict of World War II.