The War of the Quadruple Alliance (1718–1720) was a result of the ambitions of King Philip V of Spain, his wife, Isabella Farnese, and his chief minister Giulio Alberoni to retake territories in Italy and to claim the French throne. It saw the defeat of Spain by an alliance of Britain, France, Austria, and the Dutch Republic. Savoy later joined the coalition as the fifth ally. Although fighting began as early as 1717, war was not formally declared until December 1718. It was brought to an end by the Treaty of The Hague.

Causes

After the War of the Spanish Succession (1701-1714), Philippe of Anjou, grandson of Louis XIV of France, was recognized as King Philip V of Spain, but on the condition that the French and Spanish crowns would never be united.

In addition, in the Treaty of Utrecht, Spain lost all its possessions in Italy and the Low Countries. The Spanish Netherlands, Duchy of Milan, Naples and Sardinia were given to Habsburg-ruled Austria, while Sicily was awarded to the Duke of Savoy. These lands had been under Spanish Habsburg control for nearly two centuries, and their loss was perceived as a great blow to the country in both practical and prestige terms.

However, the first priority for Spain was the restoration of the country after 13 years of war, which had also been fought on Spanish territory. The main architect of this operation was Cardinal Alberoni. In 1714 he had arranged the marriage of the widowed Philip V to the 21 year-old Italian Isabella Farnese, and became the personal adviser of the new Queen. In 1715 he became prime minister, stabilized the Spanish economy and reformed finances. He also initiated the rebuilding of the Spanish fleet (50 ships of the line built in 1718) and reformed the army.

Isabella Farnese, who had several dynastic claims to advance in Italy, stimulated the Italian ambitions of King Philip V of Spain and his sons, supported by Alberoni.

In France, Louis XIV had died in 1715, leaving only one infant great-grandchild, the future Louis XV, as his successor. Philip V, the only surviving grandchild of Louis XIV, and his sons were in fact excluded from succession to the crown of France by the Treaty of Utrecht.

Philip V nevertheless claimed the French throne, in the event of the death of the infant Louis. Opposition to Philip's ambitions led France (where Louis XIV's nephew, the Duc d'Orléans, served as regent), Great Britain, and the Dutch Republic, to join together in the Triple Alliance on 4 January 1717.

Britain, in particular, had become very concerned by Spanish ambitions in the Mediterranean Sea and Russian expansion in the Baltic and dispatched fleets to both as a preventative measure. The French navy was badly weakened from the recent war, and could not offer much support.

Outbreak of conflict

Later in the year, to strengthen the Treaty of Utrecht, Britain, France and Austria contemplated ceding Sicily to the Holy Roman Emperor Charles VI. This arrangement displeased Spain, who wanted to recover the island.

Italy

In August 1717 Philip began hostilities against Austria by invading the island of Sardinia, taking advantage of the fact that Austria was tied up in the Austro-Turkish War of 1716-18. A fleet of 100 transport ships, protected by 15 warships, carried 9,000 men under command of the Marquis of Lede was assembled. It sailed from Barcelona to Sardinia, which was subdued by November 1717.

The initial Austrian reaction to this invasion was limited, as the Austrian Supreme Commander Prince Eugene of Savoy wanted to avoid a major war in Italy as long as the conflict in the Balkans continued, soaking up Austrian troops and resources. Finally, on 21 July 1718, the Treaty of Passarowitz ended the war with the Ottoman Empire and on 2 August, this led to the formation of the Quadruple Alliance, with the Emperor now joining the Triple Alliance.

Wider War

Sicily

Meanwhile, in July 1718 the Spanish, this time with 30,000 men again led by the Marquis of Lede, had also invaded Sicily, which had been awarded to the Duke of Savoy. They took Palermo on July 7 and then divided their army in two. De Lede followed the coast to besiege Messina between July 18 and September 30, while Montemar conquered the rest of the island.

The French, Austrians, and British now demanded Spanish withdrawal from Sicily and Sardinia. The attitude of Victor Amadeus II of Savoy was ambiguous, as he accepted to negotiate with Alberoni to form an anti-Austrian alliance.

Cape Passaro

On 11 August, at the Battle of Cape Passaro, a British fleet, led by Sir George Byng, captured much of a decrepit Spanish fleet.

Milazzo

In the autumn this British fleet landed a small Austrian army, assembled in Naples by the Austrian Viceroy Count Wirich Philipp von Daun near Messina, to lift the siege by the Spanish forces. This effort was not successful when the Austrians were defeated in the First Battle of Milazzo on October 15, and only held a small bridgehead around Milazzo.

Formal declaration of war

On 17 December 1718, the French, British, and Austrians officially declared war on Spain. The Dutch would join them later, in August 1719.

1719

After the discovery of the Cellamare Conspiracy, the Duc d'Orléans ordered a French army under the Duke of Berwick to invade the Basque provinces of Spain in April 1719. This army met very little resistance, but was forced back by heavy losses due to disease. A second attack in Catalonia suffered the same fate. In the Americas, the French were more successful and took Pensacola in Florida.

In Sicily, the Austrians started a new offensive under Count Claude Florimond de Mercy. They first suffered a defeat in the Battle of Francavilla (June 20, 1719). But the Spanish were cut off from their homeland by the British fleet and it was just a matter of time before their resistance would crumble. Mercy was then victorious in the second Battle of Milazzo, took Messina in October and besieged Palermo.

Scotland

It was also in 1719 that the Irish exile, the Duke of Ormonde, organized an expedition with extensive Spanish support to invade Britain and replace King George I with James Stuart, the Jacobite "Old Pretender." However, his fleet was disbanded by a storm near Galicia in 1719, and never reached Britain.

A small force of 300 Spanish marines under George Keith, tenth Earl Marischal did land near Eilean Donan, but they and the highlanders who supported them were defeated in the Battle of Glen Shiel in June 1719, and the hopes of an uprising soon fizzled out.

Vigo

In retaliation for this attack, a British fleet captured Vigo and marched inland to Pontevedra in October 1719. This caused some shock to the Spanish authorities as they realized how vulnerable they were to Allied amphibious descents, with the potential to open up a new front away from the French frontier.

Peace

Displeased with his kingdom's military performance, Philip dismissed Alberoni in December 1719, and made peace with the allies at the Treaty of The Hague on 17 February 1720.

In the treaty, Philip and Isabella were forced to relinquish all territory captured in the war. However, their eldest son's right to the Duchy of Parma and Piacenza after the death of Isabella's childless half-cousin, Antonio Farnese, was recognized.

France returned Pensacola and the remaining conquests in the north of Spain in exchange for commercial benefits. Included in the terms of this treaty, the Duke of Savoy was forced to exchange his throne in Sicily for that of the less important Kingdom of Sardinia - which would have an important bearing on the course in which the unification of Italy would later take, in the nineteenth century.

Legacy

The war provided a unique example during the eighteenth century when Britain and France were on the same side. It came during a period between 1714 and 1731 when the two countries were allies. Spain would later join with France in the Bourbon Compact, and the two would become continual enemies of the British.

The war also demonstrated the growing seapower of Britain, and the successful deployment of the Royal Navy in the Mediterranean Sea.

See also

• Villasur expedition