Historically mashed potatoes possibly go back as far as King Henry V11 (1485) which I learned in school was the starting date of the royal Tuber Period. Since then of course we have had King Edward potatoes.
You could be right masterchef. One thing I feel sure is that it wasn't Hitler; although I have heard it claimed that he was an Irishman by the name of Richard who worked in the potato fields of the Emerald Isle and emigrated to Germany where he became known as Dick Tater..!!!