According to The Nassaus of Luxembourg, Charlotte and Felix's engagement "...was announced one month before the armistice on October 6, 1918, but proved somewhat controversial. The Habsburgs had given the Bourbon-Parmas political asylum after their duchy was incorporated into the Savoy-controlled kingdom of Italy, and Felix felt obligated to offer his services to the Austrian empire during the war, though with the understanding that he would not fight on the French front as the Bourbon-Parmas considered themselves first and foremost French princes who just happened to have reigned in Italy (Pollock 66-67)."
The book goes on to say that "In June of 1915, it had been mistakenly reported that the prince had been one of the first of his unit to enter Przemysl, a disputed fortress on the Serbian front, which did not sit well with the overwhelmingly pro-Allied sympathies of the Grand Duchy. Felix was too proud to plead his own cause, but Marie-Adelaide was quick to defend him to her government. Dear God, now this good boy has to take the blame. Gentlemen, I can assure you that Prince Felix is such a charming person and in a heartbeat he would win the heart of all the Luxembourgers.. (66)"
After Marie-Adelaide's abdication, Charlotte's marriage was still the subject of some controversy, but her younger sisters would have been "equally unacceptable" as rulers, so Charlotte was named Marie-Adelaide's sucessor.
