Kingdom of Sardinia and Aosta, dynastic possessions since the 11th century, the Principality of Piedmont (a possession built up in the 13th century), and the County of Nice (a possession since 1388). While in theory the traditional capital of the island of Sardinia and seat of its viceroys was Cagliari, the Piedmontese city of Turin was the "de facto" capital of Savoy. When the mainland domains of the House of Savoy were occupied and eventually annexed by Napoleonic France, the king of Sardinia made his permanent residence on the island for the first time in its history. The Congress of Vienna (1814–15), which
Kingdom of Sardinia of the Duchy of Milan, while Charles VI (the Holy Roman Emperor and Archduke of Austria), received the Spanish Netherlands, the Kingdom of Naples, Sardinia, and the bulk of the Duchy of Milan. During the War of the Quadruple Alliance, Victor Amadeus II, Duke of Savoy and Prince of Piedmont, had to agree to yield Sicily to the Austrian Habsburgs and receive Sardinia in exchange. The exchange was formally ratified in the Treaty of The Hague of 17 February 1720. Because the kingdom of Sardinia had existed since the 14th century, the exchange allowed Victor Amadeus to retain the title