There were actually two wars: The First Sino-Japanese War was from 1894 to 1895. The Second Sino-Japanese War overlapped World war II from 1931 to 1945.
The First Sino-Japanese war was between Qing Dynasty China and Meiji Japan over the control of Korea. Because of the newly modernized Japan after the end of the three hundred year Tokugawa (Edo) Period, and the deterioation of the Qing Dynasty and its government, China lost to Japan and recognized the independence of Korea, and the last dynasty of China ended in 1912.
From there, China and Korea were under Japanese control, and so would begin many years of oppression and forced cultural assimilation from the Japanese.
The Second Sino-Japanese War began much later, between the Rupublic of China and the Empire of Japan, and was commonly known in China as "The War of Resistance Against Japan", because by this time, the Chinese were fed up with the Japanese in their country and wanted to rid China of foreign rule because of a rise in nationalism and self determination. The Second Sino-Japanese War was the largest asiatic war of the twentieth century.
Foreign aide, much from the United States, came to help China after Japan bombed Pearl Harbor.
Many plans were suppose to be put to action to secure regions of resistance in China, but after the droppings of the atomic bombs on Hiroshima and Nagasaki, Japan finally surrender.
The Chinese victory of the Second Sino-Japanese War strengthen communist and socialist views, and the People's Republic of China was formed soon after. However, because of years of oppression that were brought upon China and Korea by Japanese imperialist policy, and several war crimes committed by the Japanese Imperial Army (including mass killings, experimentation, starvation, rape and sexual slavery (see comfort women), forced labor, cannibalism, chemical weapons, looting, and torture) many Chinese and Koreans (as well as denizens of countries that were occupied by Japan such as Indonesia, the Phillipines, Thailand, Vietnam, Taiwan, and the Dutch East Indies, etc.) harbor bitter resentments toward the Japanese to this day, and no amount of compensation or apologies will ever cleanse the wounds entirely...
with a passion. What makes a lot of people - many of whom have experienced the horrors of the wars - angry is the fact that many Japanese textbooks refuse to mention any of this important and incriminating history.
Now what do you think about that, you Wapanese morons?