An aristocrat is suing the French state for €351 million ($608m) in damages for allegedly depriving his family of the throne of Monaco in order to stop it falling into the hands of a German.
Louis de Causans says that in the early 20th century France threatened to annex the wealthy Mediterranean principality if it did not change its rules of succession, the Daily Telegraph reports.
Monaco complied, thus depriving de Causans' branch of the family of his birthright and giving another offshoot of the Grimaldi family control over the city-state on the Riviera.
"Normally, in my milieu, we remain discreet and we don't like to stir up this sort of thing. But the truth must be established. It is a question of honour," said de Causans, whose full name is Louis Jean Raymond Marie de Vincens de Causans.
But he insisted that he was not aiming to dethrone his cousin Prince Albert, the current monarch of the principality and head of the princely house of Grimaldi, despite the fact that he believes that his own uncle should be on the throne today.
"I have nothing against Prince Albert, who had nothing to do with all of this. It is France which caused the damage," the 44-year-old told Le Parisien.
The dispute dates back to just over a century ago when the then Prince Louis II of Monaco had no official heir.
This meant that the next in line for the throne of Monaco was his first cousin Wilhelm, the Duke of Urach, a German nobleman.
"But for France, on the brink of World War I, the idea of a German ruling Monaco was simply unacceptable," said Jean-Marc Descoubès, de Causans' lawyer.
The throne should then have passed to de Causans' branch of the Grimaldi family, the artistocrat argues.
Instead a law was passed in 1911 recognising Louis' illegitimate daughter, Charlotte, the daughter of his cabaret singer lover Marie-Juliette Louvet, as his heir and making her part of the princely family.
This law was later declared invalid but another one was passed in 1918 that established Charlotte as the heir.
France and Monaco also signed a treaty that stated that the French Government would henceforth have the final say on all future contenders for the Monégasque throne.
De Causans' lawyer says that it is clear that the current rulers of Monaco are in their position solely by the will of the French state.
This is the base of his claim for the €351 million in damages he believes his client is entitled to, which he points out is a mere fraction of the entire wealth of the Grimaldis who rule Monaco.
He has sent his claim to the French Foreign Ministry, which has two months to respond.
If no satisfactory response is received within that time, the case will likely go to court.
"Today what I want is for the truth to come out and this injustice done to my family by France to be put right," said de Causans.