The truthfulness of events related in this legend is extremely doubtful, but since we've heard the tale from a number of different sources, we present it here without making any claims as to how real it might be:
When the princess Maria del Pozzo della Cisterna wed the duke of D'Aosta, son of the King of Italy, on 30 May 1867, the festivities were marred by such a tragic tangle of events that the royal family suppressed the truth lest the very news bring misfortune to the couple's life.
The ominous events began before the wedding when the bride's wardrobe mistress hanged herself, prompting the superstitious princess to order a new gown. The ceremony itself was delayed twice. First, the mounted officer appointed to lead the wedding procession from the palace to the church suffered sunstroke and collapsed. Then the palace gates failed to open for the matrimonial procession. The gatekeeper was found nearby, lying in a pool of blood.
Fate tendered a reprieve during the ceremony but minutes later the best man — probably ineptly handling his ceremonial weapon — shot himself in the head. Eventually the bride and groom were escorted by a procession of carriages to the railway station where the royal newlyweds were to board a train for their honeymoon. More trouble dogged their footsteps. The officer who had drawn up the marriage contract suffered a stroke and the anxious stationmaster fell under the wheels of the approaching bridal locomotive.
King Victor Emmanuel, by now dishonoured by the series of misfortunes and convinced that the ceremony and everything associated with it was jinxed, refused to allow anyone aboard the train and tried desparately to return the procession to the safety of the palace.
But it was not to be. Riding alongside the bridal carriage, the count of Castiglione fell from his horse underneath the carriage's wheels. The count died when the weight of the wheels drove a splendid medal through his uniform into his chest.