Austria had delayed implementation of the Dutch Barrier, an objective for which the Dutch Republic effectively bankrupted themselves. In January 1717, they joined France and Britain in the 1717 Triple Alliance, which reiterated the provisions of Utrecht and agreed Savoy and Austria would exchange Sicily and Sardinia. Alberoni calculated neither Britain or France would fight for these and with Austria involved in the 1716-1718 Austro-Turkish War, Spain occupied Sardinia unopposed in 1717. In early 1718, he began preparing for an attack on Sicily; unlike Sardinia, this was considered vital for British trade and in June, a naval force under Admiral Byng arrived in the Western Mediterranean as a deterrent.