In July 1856, at her sister Mary's summer residence Monrepos outside Nassau, she received a visit from Prince Oscar of Sweden, Duke of Östergötland. Oscar was the second living son of the reigning king. Following the death of his elder brother Gustaf in 1852, he had become the future heir to the Swedish throne because his brother, the reigning Crown Prince, was unable to have more children with his spouse. It was therefore politically necessary for Oscar to marry. In 1855-56, Oscar was sent to visit various royal courts in Europe in order to find a suitable marriage partner in both rank and to his own taste. He visited the British court but did not wish to marry Princess Mary of Cambridge, and the Belgian and Prussian princesses who had been suggested did not wish to marry him. The marriage of Sophia and Oscar should not be regarded as an arranged marriage: Oscar had been given the freedom to choose a princess he liked from the many courts he visited, and Sophia, who had previously been proposed to, did not wish to be pressured into marriage. Sophia and Oscar, however, mutually fell in love with each other.