Josephine was a widow with two children when she married Napoleon. He was keen to have an heir but initially Josephine was indifferent.
As she already had children (Hortense and Eugene) it was a natural assumption that it was Napoleon who had a problem. By the time she realised it was a major issue, her age came into play (she was seven years older than Napoleon).
When the young Polish Countess Marie Walewska gave birth to Napoleon’s son, Josephine knew her days were numbered. Napoleon looked around for a young wife who would bring both a royal connection and a son and heir.
He married the Austrian emperor’s eldest daughter Marie-Louise (who was also the great niece of Marie-Antoinette). Less than a year after the arrival of the 18 year old bride, she gave birth to Napoleon’s much desired son. Named Napoleon François Joseph Charles, the son was given the title of King of Rome. 
Napoleon had decided to make Rome the second capital of the empire and his son was called the King of Rome. He had grand plans for his son including a magnificent residence where Trocadero now stands.
The City of Paris presented the imperial couple with a cradle worthy of the Emperor’s heir. 
It was a magnificent creation made of gilded silver lavishly decorated with bronze and gold with the requisite eagle and winged victory among its symbols. When Napoleon was exiled on Elba, his wife took her son and his lavish cradle back to Vienna with her. It is now on display at the Hofberg Palace in Vienna.
However the governess appointed by Napoleon, had ordered other cradles – an elm wood cradle for the Tuileries Palace with its green fabric as well as another rocker for the imperial residence at Saint Cloud (also fitted with green fabric, believed to be the ideal colour for creating a tranquil environment for sleeping) . They are both on display at the Chateau of Fontainebleau.
By all accounts, Napoleon was a wonderful father.
At Compiègne he furnished Marie-Antoinette’s former apartments for the baby. The walls were left as they were in her time with new furniture added.
After he was forced to abdicate, he did so in favour of his son who would become Napoleon II. Although this was not accepted, he had expected that Marie-Louise would bring the three year old child to live with him on the island of Elba. Unfortunately she took him back to her father, the Austrian Emperor, who changed his name and raised him as an Austrian Duke, forbidding any association with France or the French. He died of tuberculosis in Schonbrunn Palace in Austria at the age of 21. For the supporters of Napoleon, he was Napoleon II which was why Napoleon’s nephew called himself Napoleon III when he took power in 1851.
The body of Napoleon’s son remained in Germany until the Second World War. Hitler made a short visit to Paris which included Les Invalides where Napoleon’s tomb takes pride of place. As a PR gesture, Hitler decided to return the King of Rome’s remains in 1940. The sarcophagus was placed in one of the chapels until 1969. On the two hundredth anniversary of Napoleon’s birth, his son was buried downstairs near his father.
