The War of the Quadruple Alliance (1718-1720) followed. It too ended in an Austrian victory; by the Treaty of The Hague (1720), Charles swapped Sardinia, which went to the Duke of Savoy, Victor Amadeus, for Sicily, the largest island in the Mediterranean, which was harder to defend than Sardinia. The treaty also recognised Philip V of Spain's younger son, Don Carlos (the future Charles III of Spain), as heir to the Duchy of Parma and Grand Duchy of Tuscany; Charles had previously endorsed the succession of the incumbent Grand Duke's daughter, Anna Maria Luisa, Electress Palatine.