The Bourbon kings officially resided in Naples, except for a brief period during the Napoleonic Wars between 1806 and 1815, when the royal family lived in exile in Palermo. The Sicilian nobles welcomed British military intervention during this period and a new constitution was developed specifically for Sicily based on the Westminster model of government. The British were committed to preserving the security of the Kingdom of Sicily so as to keep Mediterranean sea routes open against the French. The British dispatched several expeditions of troops between 1806 and 1815 and built strong fortifications around Messina