Complex sentence: Japan defeated China in the First Sino-Japanese War (1894-95), but was pressured by the Triple Intervention which included Russia, France and Germany to give up some of its territorial gains from that war.
Split into simpler sentences: Japan defeated China in the First Sino-Japanese War (1894-95). Russia as one of the three European powers of the Triple Intervention (France and Germany were the other two) pressured Japan to give up some of its territorial gains from that war.