Spanish conquest of Sardinia The Spanish conquest of Sardinia , also known as the Spanish expedition to Sardinia , took place between the months of August and November 1717 . It was the first military action between the Kingdom of Spain and the Holy Roman Empire after the War of the Spanish Succession ( 1701 – 1714 ) , and was the direct cause of the War of the Quadruple Alliance ( 1718 – 1720 ) . The Spanish troops commanded by the Marquis of Lede and Don José Carrillo de Albornoz , 1st Duke of Montemar , supported by the Spanish fleet , defeated the Emperor ' s troops easily , and conquered the entire island of Sardinia , which had been ruled by the Emperor since the Treaty of Rastatt ( 1714 ) , returning it again and for the final time to Spain . Background . After the War of the Spanish Succession , with the Treaty of Rastatt , Spain lost all its possessions in Italy and the Low Countries . The Spanish Netherlands , the Duchy of Milan , the Kingdom of Naples and Sardinia were given to Austria , while Sicily to the Duke of Savoy . These territories had been under Spanish rule for nearly two centuries , and their loss was perceived as a great blow to the country in both practical and prestige terms . < ref name = " Laínez / Canales219 " > Laínez / Canales p . 219 < / ref > In 1717 , with the rise of Spain as an important military power again , and the ambitions of the King Philip V of Spain to regain the Spanish supremacy in Italy and the Mediterranean , the rest of the European powers , Great Britain , France and Austria , to strengthen the Treaty of Utrecht ( 1713 ) , contemplated ceding Sicily to the Holy Roman Emperor Charles VI , but this arrangement displeased Spain , who wanted to recover the island . With this background , and the arrest in Milan from Spanish Grand Inquisitor , Jose Molina , by the Austrians , Philip V obtained the pretext he sought . In July , the King of Spain , ordered to the Spanish fleet , prepared in Barcelona , conquer Sardinia , initiating hostilities with Austria . The bulk of the Spanish expedition sailed from the port of Barcelona on July 24 , and on 30 July , sailed the rest of the fleet . The fleet , under the command of the Marquis de Mari , consisted of 9 ships of the line , 6 frigate s , 3 galley s , 2 fireship s and 80 transport and merchant ships , and the troops , were composed by 8 , 500 infantry and 500 cavalry commanded by Don Juan Francisco de Bette , Marquis of Lede . On 22 August , the Spanish forces landed in Sardinia , and in just two months reconquered the whole island , whose defenses were commanded by the Marquis of Rubi . The quick victory was mainly due to the psychological action of the Marquis of San Felipe , who toured the island by encouraging its inhabitants , who were not happy with the Austrian dominion , preferring to return under the Spanish rule . Only the strengths of Alghero , Aragonese Castle in the Ischia Island , and of the important city of Cagliari resisted , but soon the Austrian troops in Cagliari commanded by Rubi , in the absence of reinforcements , decided to flee to the north of the island , and on 4 October , the Spanish troops took the city . A few days later , on 19 October , the bulk of the Spanish troops led by the Marquis of Lede and the Duke of Montemar laid siege to Alghero , and finally capitulated on 25 October . The last place fell to 30 October , and the Spanish victory was complete . Consequences . The initial Austrian reaction to this invasion was limited , because Austria had put all their resources on Austro - Turkish War of 1716 - 18 , and the Austrian supreme commander , Prince Eugene of Savoy , wanted to avoid a great war in Italy with Spain . The Treaty of Passarowitz ended the war between the Ottoman Empire and Austria , and on 2 August , this led to the formation of the Quadruple Alliance . Meanwhile , in July , 1718 , the Spaniards , this time with 30 , 000 men , including four regiments of " Dragoons " , again led by the Marquis of Lede , and a fleet of 350 ships , and over 250 pieces of artillery , invaded Sicily . The Spanish forces captured Palermo on 7 July , and then divided their army in two . De Lede followed the coast to besiege Messina between 18 July and 30 September , while the Duke of Montemar conquered the rest of the island . The French , Austrians , and British demanded the Spanish withdrawal from Sicily and Sardinia . The attitude of Victor Amadeus II of Savoy was ambiguous , as he accepted to negotiate with the Spanish Prime Minister , Cardinal Alberoni , to form an anti - Austrian alliance .