The only record of which I am aware giving Owen Frederick Warner's DoB is the 1900 census and it gives onlt Apr 1884.
There are quite a few online genealogies that giv a date of 1984 as the DoD. I have not been able to verify that
Many sources give the name as Owen T Warner. That is the result of a transcription error in the 1900 census. A close comparision of the middle initial with other examples on the same page (e.g. Ermina F Warner, whose middle name was Frances) shows that it is 'F' not 'T'. Of note is that most later sources have Frederick O or Frederick Owen, not Owen as the first name, including his WWI draft registration, which was probably signed by his father, George Washington Warner.
