You may have to accept the issue that you may never find out. Our former President Harry S. Truman for example had an S as a middle initial. What did the S stand for? Some people say that it stood for each of his grandfathers names. Some say nothing at all. You may find the answer if you continue looking? I would focus somewhat on his parents and where they were from. Find issues such as did he have any children? If so and they lived after 1913 they may have a death certificate and that might provide his name rather than initials. I believe you have already been given the advice of looking into his pension records if he received any and that is an issue I would look into. Also he may have provided information for another soldier's pension. Check into Company D and find out who some of the soldiers were. He may have been a witness for a pension as an example. Once you have established where he was living you might check into the counties property records and or tax records. Some larger libraries now have a useful tool. They have a pay site that can track down names in various newspapers from across the country and can tell you what page and newspaper had the items. Family Bibles may also lead you to your answer. The Mormon library in Salt Lake City, Utah which I visit on occasions may provide some clues. It may also be worth your time by going to the National Archives, in Washington DC. Hiring a professional genealogist may be another avenue to explore. Because he appers to have been a rather important person, your chances are good you may turn up something at NARA. Sometimes your answer may come when you least expect it. Keep looking and trying. No one ever said it was easy. Finding the answer yourself is much more rewarding. Hoping for your success. Thx Dennis