Hi, everyone! There are quite often queries here about when and why middle names came into use. At the moment I'm reading a history of the Mediterranean: The Middle Sea, by the wonderfully named
John Julius Norwich. As far as I can tell, it makes pretty scholarly use of the available (secondary?) sources ...
And on p 153 we find a reference to the birth and youth of
Frederick II, Stupor Mundi: " … the child – named
Frederick Roger, after his two grandfathers – was crowned
King of Sicily." This was four years after his birth in 1194, and provides a very early reference to
Royal naming habits.
Fast forward to the Sixth Crusade, 1250, and a disastrous expedition led by St
Louis of
France was slightly ameliorated by the good behaviour of his wife
Margaret, who managed to pay the ransom for
Louis and his surviving men. While this was going on, she gave birth and "named her little son
John Tristan, "the child of sorrow'".
I found these very interesting, though of course there's no indication of how many people, royal or not, followed suit. Any further info would be good, if anyone has some.
All the best