The Rothschild banking family of Naples () was founded by Calmann (Carl) Mayer von Rothschild (1788–1855) who was sent to the Kingdom of the Two Sicilies from Frankfurt am Main, Germany in 1821. Endogamy within the family was an essential part of the Rothschild strategy in order to ensure control of their wealth remained in the family's hands. Through their collaborative efforts, the Rothschilds rose to prominence in a variety of banking endeavors including loans, government bonds, and trading in bullion. Their financing afforded investment opportunities and during the 19th century, they became major stakeholders in large-scale mining and rail transport ventures that were fundamental to the rapidly expanding industrial economies of Europe. By 1820, N M Rothschild & Sons bank was already operating successfully in London, England, de Rothschild Frères in Paris, and S M von Rothschild in Vienna, Austria where Salomon Mayer von Rothschild became a powerful ally of Austria's Prince Klemens Metternich. In March 1821, in support of King Ferdinand I of the Two Sicilies, the Austrian army entered the Sicilian Kingdom and occupied Naples. This event opened the door to the Rothschild interests and Carl von Rothschild was sent to Naples where he established C M de Rothschild & Figli to operate as a satellite office to the Rothschild banking family of Germany headquarters in Frankfurt am Main. Elevation to Austrian nobility In 1822, the five Rothschild brothers at the head of the family's banks in various parts of Europe were each granted the hereditary title of Freiherr (baron) in the Austrian nobility by Emperor Francis I of Austria (formerly Francis II, the last Holy Roman Emperor). As a result, some members of the Rothschild family used the nobiliary particle de or von before their surname to acknowledge the grant of nobility. Involvement in finance and industry Carl von Rothschild developed a good working relationship with Luigi de' Medici, the "Direttore della Segreteria di Azienda del Regno di Napoli" (Finance Minister), and his operation became the dominant banking house in Naples. As a result of Carl's success, the Rothschilds had a substantial banking presence in England and three other major European capitals, giving the family considerable influence and an advantage over their competitors. During the winter of 1826, Leopold of Saxe-Coburg, future King of the Belgians was a guest of Carl von Rothschild at his villa in Naples. In 1829, he was appointed consul-general of Sicily