Answers for the beginner, the befuddled and anyone hitting a brick wall.
Q. My great-grandfather was a member of the Prussian Garde du Corps before 1884. Where can I learn more about the Garde and my great-grandfather's service?
A. First, you must make sure your ancestor really was part of the Prussian Garde du Corps, which began in 1740 as an elite cavalry unit and became the German emperor's bodyguard. If all stories about such service were true, elite units wouldn't be very elite. You'll need to be open to the possibility that your great-grandfather was in some other unit, in case his Garde membership is just a family story.