Fantastic War
The Spanish–Portuguese War was fought as part of the Seven Years' War. The first and main theatre of the war was an invasion of Portugal by Spain in alliance with France against the Anglo-Portuguese Alliance, which ended after three disastrous invasions. The second theatre was a Spanish invasion of Portuguese colonies in South America. Though tactically successful for the Spanish in the strategically important area on and near the River Plate, their gains there were largely given up in the peace negotiations, resulting in a strategic success for the Portuguese in South America.
Because no major battles were fought in the Portuguese segment of the war, even though there were numerous movements of troops and heavy losses among the Franco-Spanish invaders, this theatre of the Seven Years' War is known in Portuguese historiography as the Fantastic War in the sense of phantom war, due to the successful Portuguese strategy of starving the invading Franco-Spanish army of supplies while avoiding or minimising pitched battles.
The war ended along with the Seven Years' War in the 1763 Treaty of Paris.
Background
When the Seven Years' War between France and Great Britain started in 1754, Spain and Portugal remained neutral, their differences in South America having been settled by the Treaty of Madrid of 1750. Ricardo Wall, prime minister to King Ferdinand VI of Spain, was opposed to the pro-French party at court who wanted to enter the war on the side of France.All this changed when Ferdinand died in 1759 and was succeeded by his younger half-brother Charles III. The more ambitious Charles was motivated to preserve Spain's position as a leading European and colonial power. By 1761 France looked to be losing the war against Great Britain. Fearing a British victory over France, Charles signed the Family Compact with France in August, and claimed compensation for attacks by English privateers in Spanish waters. This brought war with Great Britain in January 1762. Portugal had been weakened by the disastrous 1755 Lisbon earthquake, leading Prime Minister Sebastião José de Carvalho e Melo, Marquis of Pombal, to direct all efforts towards the reconstruction of the country and neglected the armed forces, in which he had little interest. A new treaty between Spain and Portugal, the Treaty of El Pardo of 1761, rendered the Treaty of Madrid null and void.
At the urging of the French government, Spain agreed to attack Portugal, which had been neutral, but served as an important economic ally of Great Britain. The invasion was not intended to conquer Portugal but to create a new front that would draw away British forces, now directed against France.
The third Franco-Spanish invasion of Portugal in Europe, on 5 May 1762, was followed by a Spanish invasion of Portuguese territories in South America. While the first ended in humiliating defeat, the second represented a stalemate: Portuguese victory in remote areas in northern and western Brazil; Spanish victory in the strategically sensitive area on and near the River Plate.
Peninsular theatre
During the war, a Franco-Spanish army of about 42,000 men, first led by Nicolás de Carvajal, Marquis of Sarria and then by Pedro Pablo Abarca de Bolea, 10th Count of Aranda, invaded Portugal in 1762, in three different regions at three different times: provinces of Trás-os-Montes, province of Beira and Alentejo. They were faced by ferocious popular resistance and, from the middle of the second invasion onwards, by an Anglo-Portuguese army of nearly 15,000 men commanded by William, Count of Schaumburg-Lippe.In the first invasion, the Spanish – whose final goal was Porto, the second city of the kingdom – occupied without opposition several undefended towns and ruined fortresses of the Trás-os-Montes Province; there were neither regular soldiers nor gunpowder in the entire province, except in the fortress of Miranda do Douro. However, guerrillas exploited the mountainous nature of the province to cut off the invaders' supply and communication lines with Spain as well as to inflict heavy losses. The Portuguese abandoned their villages, inducing famine among the Spaniards, who launched two offensives towards Porto: the first was defeated by the militia and peasants at the Battle of Douro and the second was beaten off at the mountains of Montalegre. This failure and the arrival of Portuguese reinforcements forced the now diminished Spanish army to retreat into Spain, abandoning all their conquests. After this defeat, the Franco-Spanish commander, Sarria, was replaced by the Count of Aranda.
During this first invasion of Portugal, the total Spanish casualties, according to a contemporaneous French source, Charles François Dumouriez, were 10,000 men: prisoners, deserters or deaths by hunger, guerrilla ambushes and disease.
At the request of Portugal, one British force of 7,107 soldiers and officers landed in Lisbon, deeply reorganizing the Portuguese army. The supreme command of the allied army was delivered to one of the best soldiers of his time: the Count of Lippe.
In the beginning of the second invasion, the Franco-Spaniards captured several poorly equipped Portuguese fortresses and towns, including Almeida. However, the Anglo-Portuguese army defeated a Spanish corps which was preparing another invasion through the province of Alentejo at the Battle of Valencia de Alcántara, and foiled the Spanish attempt to cross the river Tagus, defeating them at Vila Velha.
The allied army eventually stopped the Bourbon army's march toward Lisbon in the mountains near Abrantes and used a scorched earth strategy – in cooperation with the rural population – to starve the invaders: peasants abandoned their villages, destroying or taking with them all the food, while the guerrillas attacked their logistic lines. The invaders had to choose between stay and starve or withdraw.
The outcome was the destruction of the Franco-Spanish army, whose remnants – leaving their wounded and sick behind – were chased to Spain by the Anglo-Portuguese army and peasants, after two encirclement movements undertaken by a Portuguese force under General George Townshend, 1st Marquess Townshend toward the enemy's rear: the first move forced the Bourbons to withdraw from the hills east of Abrantes to Castelo Branco, while the second made them flee to Spain. The Spanish headquarters, was captured by the allied army, which took thousands of prisoners.
The total Franco-Spanish losses in this second invasion were evaluated by a contemporaneous Bourbon source as 15,000 men, while the total casualties for both the invasions were about 30,000 men, according to the British minister in Portugal, Edward Hay.
As explained by historians Danley Mark and Patrick Speelman:
During the third Spanish offensive, the Spaniards attacked by surprise two Portuguese towns – but were defeated - and had to retreat again before the reinforced and advancing Anglo-Portuguese army, which took some prisoners. Additional Spanish prisoners were taken when a Portuguese force led by British Colonel Wrey entered Spain and attacked the region of Codicera on 19 November.
Thus, Aranda, with his forces ruined and demoralized, sent to Lippe an emissary proposing an armistice on 24 November, which was accepted and signed on 1 December 1762.
South American theatre
River Plate
In South America, the Spanish Cevallos expedition was more successful. In present-day Uruguay, they captured Colónia do Sacramento and two other fortresses: fort of Santa Teresa, on 19 April 1763; and fort of San Miguel, in 23 April.Southern Brazil
Cevallos advanced and won a still greater victory when he conquered most of the vast and rich territory of the so-called "Continente de São Pedro do Rio Grande do Sul" – the present-day Brazilian state of Rio Grande do Sul, where the Portuguese had only up to 1,000 men. São José do Norte and the capital – S. Pedro do Sul- were abandoned without a fight. However, the Spaniards were routed by the Portuguese in the Battle of Santa Bárbara, when an invading army of 500 Spaniards and 2,000 Indians, in cooperation with Cevallos, tried to conquer Rio Pardo, nearly the only remaining Portuguese territory in Rio Grande do Sul: seven cannons, 9,000 head of cattle and 5,000 horses were captured.This huge territory would be completely retaken by the Portuguese during the so-called "deaf war".