Quadruple Alliance, any of several European alliances. The Quadruple Alliance of 1718 was formed by Great Britain, France, the Holy Roman emperor, and the Netherlands when Philip V of Spain, guided by Cardinal Alberoni, sought by force to nullify the peace settlements reached after the War of the Spanish Succession (see Utrecht, Peace of). An English fleet landed Austrian troops in Sicily, which Spain had seized, while French and English forces entered Spain. Early in 1720, Spain yielded to the allies, but the peace terms thoroughly revised those signed at Utrecht. The Treaty of The Hague restored Naples to the house of Austria; Austria in turn promised that Philip's son Charles (later Charles III of Spain) would succeed to Parma, Piacenza, and Tuscany. Savoy, in exchange for yielding Sicily to the house of Austria, received the island of Sardinia and became the kingdom of Sardinia. Spain joined the alliance. A progressive rapprochement between Spain and France led to the Family Compact of 1733 and a further redistribution of territories after the War of the Polish Succession (1733–35). The Quadruple Alliance of Mar., 1814, was concluded among Great Britain, Austria, Prussia, and Russia at Chaumont, France, in order to strengthen their coalition against Napoleon I. After Napoleon's first abdication the four powers made peace with France (see Paris, Treaty of, 1814); after Napoleon's return from Elba, they defeated him in the Waterloo campaign and imposed on France the more severe Treaty of Paris of 1815. On the same day that treaty was signed (Nov. 20), the Quadruple Alliance was renewed in order to insure the treaty's execution. The so-called Holy Alliance, signed a few days earlier by Russia, Austria, and Prussia, became confused with the Quadruple Alliance, especially since the international congresses at Aachen (1818), Troppau (1820), Laibach (1821), and Verona (1822)—which were held according to provisions of the Quadruple Alliance—increasingly shaped the policy of the Holy Alliance, while England retired into "splendid isolation." In 1818, France joined the powers of the Quadruple Alliance to form a Quintuple Alliance. The Quadruple Alliance of 1834 was formed by Great Britain, France, Spain, and Portugal for the purpose of strengthening the constitutional government of Spain and the throne of Isabella II against the Carlists. The Spanish marriages (1846; see Isabella II) ended Franco-British cooperation in Spanish affairs.