"By the end of the nineteenth century, assimilation as a theoretical construct for colonial policy had come to be associated with French colonial policy. Direct rule rhetoric promised its recipients benefits reserved for those colonized as internal citizens, yet in practice the policy treated these peoples as marginalized subjects. Indirect rule, favored by the English, advanced separate colonized-colonizer existences, and its practitioners generally governed their charges in this spirit. Contrary to this distinction, close examination of these colonial histories reveals that while the French philosophized on assimilation and invited a small, but diverse, number of colonized to their parliament, their assimilation practices hardly approached the ambitious inclusive goals trumpeted by Enlightenment thinkers. The English, on the other hand, practiced indirect rule in most of their colonies but also introduced assimilation practices in others. While the french trumpeted assimilation as a universal right to all peoples, the English quietly introduced the practice in a more practical way, as one applicable to a selection of its peripheral possessions. While the French demanded cultural rebirth as a prerequisite to assimilation, the English incorporated assimilated peoples as political subjects, without requiring (but occasionally prodding) them to adopt English culture."
Mark Caprio, Japanese Assimilation Policies in Colonial Korea, 1910-1945, pg 22
The general idea is that between these two competing ideas, the Japanese, in regards to Taiwan and Korea, picked the French path, under the assumption that since Koreans and Taiwanese were so close genetically and culturally (Confucianism, kanji, etc) they would adopt Japanese language and culture quickly, within 30 years or so. In practice, however, the French never really accepted any colonial subjects as “French,” even the Algerians, and so the system never completely worked out in the end.