In 1852, not long after Napoléon III became Emperor of France, he made a proposal of marriage to Adelheid's parents after he had been rebuffed by Princess Carola of Sweden. Although he had never met her, the political advantages of the marriage for the Emperor were obvious. It would provide dynastic respectability for the Bonaparte line, and could promote a closer alliance between France and Britain, because Adelheid was Queen Victoria's niece. At the same time, she was not officially a member of the British royal family, so the risk of refusal was small. Adelheid could be expected to be grateful enough for her good fortune to convert to Roman Catholicism.