A Jewish banking family whose members exerted considerable influence on both economic and political affairs during the 19th and early 20th centuries. Mayer Amschel Rothschild of Frankfurt, who became financial adviser to the Landgrave of Hesse-Kassel, founded the Rothschild banking house in the 18th century. He and his five sons prospered in the years of the Revolutionary and Napoleonic Wars and moved to London in 1804. They loaned money for the raising of mercenary armies and negotiated means of bypassing Napoleon's Continental System. After 1815 Rothschild houses were opened as a banking group in all the great cities of Europe. Of Mayer's sons, Anselm (1773–1855) became a member of the Prussian privy council, Salomon (1774–1855) became financial adviser to Metternich in Vienna, and Nathan (1777–1836) established a branch of the bank in London. His son, Lionel (1808–79), became the first Jew to sit in the British House of Commons (1858) and he lent the British government £4 million in 1875 to buy the Suez Canal shares. His son Nathan (1840–1915) was the first British Jewish Peer and became regarded as the unofficial head of both French and British Jewish communities. It was to his son Lionel Walter (1868–1937), the second Baron and distinguished scientist and scholar, that the Balfour Declaration was addressed in 1917. The Rothschilds are still prominent in banking in Britain and are notable patrons of the arts and sciences.