Yet it was only when I had to assist my son for the first time with his homework, which happened to concern the siege of Lisbon in 1147, that I started to learn more.
I knew that the Aliança Luso-Inglesa had been established since 1386, and that it "is the oldest alliance based on known history in the world that is still in force by politics". Yet I hadn't realised the historical depth of this relationship between the two countries.
This was as a result of discovering that it was specifically the contribution of a crusading army on their way to the second crusade, predominately made up of Englishmen, that were crucial to the successful liberation of Lisbon. Having been forced by weather to stop at Porto on their way to the Holy Land, they were convinced by Alfonso I to assist in the siege (with the promise of the pillage of the city's goods, and the ransom money for prisoners). This proved a successful outcome, and also resulted in the transfer of the knowledge of siege engines and related technology from the English to the Portuguese which was to prove of great assistance during the following reconquista. The significance of this is illustrated in the famous painting by Alfredo Roque Gameiro.
Many of these crusaders decided to stay in Portugal afterwards, one of whom was Gilbert of Hastings, the first Christian bishop of Lisbon since the Moorish invasion of 716 AD.
The treaty that legally, militarily and politically exists between England and Portugal was the Anglo-Portuguese Treaty of 1373. This solidified the relationship, and formed an alliance against Spain, and is the oldest continuous international treaty in effect to this day.
The background to this was a conflict between England and Spain led by John of Gaunt, Duke of Lancaster. He sealed the alliance through the marriage of his daughter Philippa to John I of Portugal, and their marriage produced 5 sons that would become known as the “Illustrious Generation” or “Ínclita Geração”. The most famous of these half-English princes was Prince Henry the Navigator, a central figure in Portuguese history and the Age of Discoveries.
In addition to mutual military assistance, this also resulted in increased cultural and business co-operation. Philippa provided royal patronage for English commercial interests that sought to meet the Portuguese desire for cod and cloth in return for wine, cork, salt, and oil shipped through the English warehouses at Porto. It is likely that the Portuguese affection for bacalhau is due to learning from the English the practice of salt-based curing in the Newfoundland cod fisheries.
Subsequent to this, another Englishman was engaged in military service for Portugal, but it was to prove much less successful. The famous adventurer Thomas Stukley was engaged by King Sebastian of Portugal to assist in the invasion of Morocco in 1578, and was killed at the Battle of Alcácer Quibir. This military disaster for Portugal ultimately led to a succession crisis and the Portugal-Iberian Union of 1580 to 1640.
This was the only interlude of the alliance, during which Portugal’s foreign policy was controlled by the Spanish. During this period, the Philippine dynasty, Portugal lost many of its colonies and Spain's enemies became Portugal's. Nevertheless, during this time England still provided financial and military support to the claimants to the Portuguese throne against the Spanish, in particular for António, Prior of Crato.
Assistance was also given during the Portuguese restoration war. The marriage of Catherine of Braganza to Charles II in 1662 again cemented the relationship between the two countries. The Portuguese were bolstered by the arrival of a British brigade which numbered 3,000 in August 1662, and they proved to be a decisive factor in winning back Portugal's independence, playing a key role in the Portuguese victory in the battle of Ameixial.
During the seven years war, the UK intervened again to assist the resistance to the Spanish/French invasion of Portugal in 1762. It was a British reinforcement that proved to be instrumental in the victory of the Battle of Valencia de Alcántara, and forced the retreat of the invading forces.
One of the best known examples of this mutually beneficial co-operation is the Peninsular war. As a result of the long-standing economic, cultural and military relationship between the two countries, Portugal refused to join the continental system against Britain, and so Napoleon invaded. The British intervention was again instrumental in a hard fought war that made the reputation of the Duke of Wellington (and Sharpe!) prior to Waterloo, and pushed the French back over the Pyrenees.
The military co-operation between the two countries continued in both World Wars of the twentieth century. During WW2 Churchill credited Salazar with keeping Portugal neutral and restricting the supply of tungsten vital to the Wehrmacht, and by allowing the usage of bases and airfields in the Azores and elsewhere that was crucial to winning the battle of the Atlantic against Nazi Germany.
Access to airfields in the Azores would also be crucial to the successful outcome of the Falklands War in 1982, these were logistically crucial to the ability of the RAF to conduct combat operations.
Throughout the length of the history of this alliance and collaboration, it has not only been extremely close and mutually beneficial, but truly unparalleled in history.