As the only legitimate son of Napoleon I, he was already constitutionally the Prince Imperial and heir apparent, but the Emperor also gave his son the style of King of Rome. Three years later, the First French Empire collapsed. Napoleon I saw his second wife and their son for the last time on 24 January 1814. On 4 April 1814, he abdicated in favour of his three-year-old son after the Six Days' Campaign and the Battle of Paris. The child became Emperor of the French under the regnal name of Napoleon II. However, on 6 April 1814, Napoleon I fully abdicated and renounced not only his own rights to the French throne, but also those of his descendants. The Treaty of Fontainebleau in 1814 gave the child the right to use the title of Prince of Parma, of Placentia, and of Guastalla, and his mother was styled the Duchess of Parma, of Placentia, and of Guastalla.