de Broglie, P and D

I'm nearing the end of the B's in my Britannica, and I came across
mention of the distinguished family of de Broglie. Originally
Italian, they migrated to France and provided several generations of
soldiers and statesmen.

The family has a French dukedom and a HRE princely title.

The 6th duke's younger brother (Louis Victor, 1892-1987) was the
famous Nobel-prize-winning physicist. The elder brother used the
title of duke and the younger used the title of prince.

I'm a bit puzzled that it wasn't the other way around. Does anyone
know some of the history here?

For instance, is an HRE princely title considered less than a French
ducal one? Or is this just the practice in this particular family,
not an application of general principle?

mjcar...

In addition to the explanations provided by other posters, I wonder
whether a British analogy might be useful here, viz branches of the UK
royal family which hold Dukedoms. For instance, the HRH the Duke of
Kent, having succeeded to that peerage, is never known by his princely
title, whereas his younger brother (who has no peerage) invariably uses
his - ie Prince Michael of Kent.

edespalais...

The B are a noble family, not a sovereign one. When one received or
could receive a French rank of duke, the corresponding HRE title was
prince. If a (French) dukedown exists is unknown. The HRE title is
such, that everybody hold the title F=FCrst, prince en Fran=E7ais.
Difference between head of a family and the "cadets" (pu=EEn=E9s),
the first one was in that sense poorer that he did not wear a first
name.

cbstewart3rd...

Neither. In Germany and France, Duke is normally a higher title than
prince. When princes outranked dukes in those realms, it was because of
their status (as cadets of a grand ducal, royal or imperial dynasty)
rather than because of their title. See:

Guy Stair Sainty...

Not only that, the Ducal title is a French one, and further more a Duche-Pairie
(Duke-Peer), while the princely title is a foreign title. There is no higher
rank in the French nobility than Duke-Peer.

Under the French Empire, the title of Prince was higher, but following the
restoration the princely titles were in most case ignored, untand their
holders were in most cases stronger loyalists to Napoleon. Berthier and
talleyrand lost their sovereign principalities, even though Talleyrand continued
to use his princely title, he was created a Duke-Peer. henceforth
one saw the old Napoleonic Princes - such as Berthier, who was Duc de Wagram and
prince de Neufchatel under the Empire, become the "Prince Duc de Wagram" under
the Restoration, as a Duke-Peer. Tallerand's cousin, the Prince de Chalais, who
was made duke-peer, became the Prince Duc de Chalais. As such,
however, they ranked exactly as if they wree dukes, as being a Prince Duke
did not giv eone higher status.

Stan Brown...

Thanks, Guy. That makes sense to me now. The elder son used the ducal
title because it was natively French and it was attached to a peerage
(though that no longer had legislative significance).

One question: Les Amis de Talleyrand[1] say that T. received a
_princely_ title under the Restoration of Louis XVIII: "Le 4 juin
[1814], Charles-Maurice reçoit le titre de Prince de Talleyrand et
est nommé Pair de France." So he would have been a prince-peer, if
I'm reading that correctly.

According to that same page, Talleyrand didn't become a duke till 31
Aug 1817, over three years later. The page doesn't say whether he
renounced his title of "Prince de Talleyrand", but since it had been
granted by the same monarch I don't imagine it would have been
necessary.

Charles Stewart