The wedding was controversial because the bride, Eugenia de Montijo, was only a countess by her stock.
On January 30, 1853, the last imperial wedding took place in France. Namely, the reigning Emperor Napoleon III. Bonaparte married Spanish noblewoman Eugenia de Montijo. This marriage was quite controversial, as the bride-to-be was only a Countess, who was considered by many to be ridiculously unworthy of an emperor’s wife.
Napoleon III. he was indeed trying to find the bride from slightly higher circles, but was rejected, because the ruling European dynasties were not sure that he would be held on the imperial throne (indeed he was overthrown later, and in a shameful way). Napoleon III. in the end he chose a beautiful Spain, and when declaring his engagement he said that he favors a woman he loves and respects over one that would bring him some advantages but does not know her. In this way he expressed contempt for the royal widowers, whom he seemed to be rejected.
Although she was not of royal descent, Eugenia was actually quite blue in blood. Her father was a Spanish aristocrat with typical bombastic titles for the country: 13th Duke of Peñaranda del Duero, 14th Marquis of La Bañeza, 14th Marquis of Miralla, 13th Marquis of Valdunquilla, 9th Marquis of Valderrában, 8th Marquis from Osere, 16th Marquis of Villanueva del Fresno y de Barcarrot, 8th Earl of Monti, 12th Earl of Baños, 19th Earl of Santa Cruz de la Sierra, 18th Earl of Miranda del Castañar, etc. etc.
Interestingly, Eugenia’s mother was of unusual Scottish-Belgian aristocratic origin, and it was she who allegedly gave the famous writer Prosper Mérimée an idea for the character Carmen (later celebrated in opera).