The Emperor Charles IV confirmed the right of the Imperial Election to Frankfort by the famous Golden Bull issued in 1356. This Bull provided the Emperor Napoleon with an opportunity for displaying his excellent memory. Dining one day with half a score of sovereign princes, at the meeting of Erfurth, the conversation chanced to turn on the Golden Bull, which, until the Confederation of the Rhine, had laid down the rules for Imperial elections. The Prince Primate, being on his own ground, gave some details concerning the Bull, fixing the date for 1409. "I think you are mistaken, prince," said Napoleon. "If my memory is correct, the Bull was published in 1356 in the reign of the Emperor Charles IV." "Your Majesty is right," said the primate, reconsidering, "but how is it you remember the date of a bull so exactly? Had it been a battle it would be less wonderful." "Shall I tell you the secret of this wonderful memory, prince?" enquired Napoleon. "Your Majesty would give us all much pleasure." "Well," continued the emperor, "you must know that when I was a sub-lieutenant in the Artillery--" Whereupon there was so decided a movement of surprise and curiosity among the illustrious guests that Napoleon paused an instant, but seeing that all were waiting for him to continue, he resumed with a smile: "I was saying that when I had the honour of being a sub-lieutenant of Artillery I was in garrison at Valence for three years. I did not care for society, and lived very quietly. By a lucky chance I had rooms opposite a well-read and obliging bookseller, whose name was Marcus Aurelius, and who gave me the run of his library. I read and re-read everything in his shop two or three times during my stay in the capital of the Drôme, and I remember everything I then read--even to the date of the Golden Bull." Frankfort continued to govern itself as a free imperial town until, after having been bombarded by the French in the wars of the Revolution, it was one fine day handed over by Napoleon to the Prince Primate Charles of Dalberg, when it became the capital of the Grand Duchy of Frankfort.