They conquered Korea, parts of China (Taiwan, Manchuria), in WW1 they briefly occupied the German territories in the Pacific (but got practically none of them at the end of the war). read more
Fought between Qing China and Meiji Japan officially from Aug 1, 1894 to April 17, 1895 ( fighting broke out on July 25, 1894 ) over control of Korea, which was a Chinese tribute state, Japan proved victorious over this war. Ended with the Treaty of Shimonoseki. read more