Complex sentence: In 1884 he returned as a diplomat working for the U.S. Government and continued in that role until relieved of his post in 1897, after which he was the Japan representative of the Standard Oil company.
Split into simpler sentences: In 1884 he returned as a diplomat working for the U.S. Government and continued in that role until relieved of his post in 1897. After 1897 he was the Japan representative of the Standard Oil company.