With military victory in the Iberian Peninsula and a Plantagenet on the Castilian throne, it would only be a matter of time before France would be forced to the negotiating table. It was believed the answer to the strategic stalemate lay in the “Chemyn de Portugal” and the “Chemyn d’Esapigne” the “way of Portugal” and the “way of Spain” a reference to the policy of military intervention in Iberia. A notary’s mark found at the bottom of some diplomatic documents would often be employed to ensure no space was left for a document to be tampered with or added to. Treaty of alliance between king Edward III of England and Ferdinand I of Portugal, 16th June 1373 (The National Archives: E 30-275) A notary mark drawn by the clerk. Added to this was a dynastic interest as the Duke of Lancaster, John of Gaunt, had a legitimate claim to the throne of Castile through his wife, Constance, daughter of Peter the Cruel (1334-1369).īelow is the treaty of alliance sealed in 1373 between King Edward III and King Ferdinand I of Portugal ( The National Archive: E 30/275). Therefore closer union with Castile’s western neighbour Portugal was a logical step to counter this threat. Through the alliance with Castile, which had one of the largest fleets in Western Europe, France could utilise Castilian sea power, in its struggle against England. Fourteenth century Anglo-French relations mostly alternated between hostile rivalry at best to periods of open conflict and war at worst. An alliance between France and Castile (precursor to the kingdom of Spain) in 1369 had caused consternation at the English court. The Anglo-Portuguese alliance had in fact been born primarily out of converging strategic interests. So how did this alliance - the longest continuing alliance in global history - transpire? Origins The seals attached to the document are those of the Portuguese ambassadors: Ferdinand Afonso de Albuquerque, Master of the Portuguese military order of St James and Chancellor of Portugal Lawrence John Fogaca entrusted as plenipotentiaries in the treaty negotiations. There were even clauses encouraging freedom of movement and settlement between the two countries, as subjects of either country had the right to dwell in the domains of the other. The terms of the treaty included provisions for guaranteeing the mutual security of both nations and strengthening of commercial ties such as the right of both countries to trade on the terms enjoyed by the subjects of that country. Though it is not the earliest of the Anglo-Portuguese treaties that survive, the Treaty of Windsor is significant because it effectively cemented and strengthened ties between the two kingdoms and helped convert a fledgling alliance into a more permanent legacy of history. It is 630 years since a treaty of alliance between King Richard II of England and King John I of Portugal was ratified at Windsor on the 9 th May 1386 ( The National Archives: E 30/310). Winston Churchill in a speech in the House of Commons in October 1943 famously described the unique and ancient friendship between England and Portugal as an alliance “without parallel in world history”. The Treaty of Windsor sealed on 9th May 1386 (The National Archives: E 30/310) Seal of the Portuguese ambassador, Fernao Afonso de Albuquerque, Master of the Portuguese military order of St James (The National Archives: E 30/310)