The Longest Diplomatic Partnership in History Began with a Treaty in 1373
In short: England and Portugal share the longest continuous alliance in history, a bond forged in the fires of the Hundred Years War. From medieval crusading knights to the Napoleonic Wars, this enduring partnership has shaped European geopolitics for 650 years. Discover the origins and the commerce that keep this friendship alive.
The formal alliance between England and Portugal was established on 16 June 1373, when King Edward III of England signed a treaty with King Ferdinand and Queen Leonor of Portugal. This agreement, sealed at St. Paul’s Cathedral in London, was a strategic response to the Hundred Years War. France had aligned itself with Castile, Portugal’s neighbor, prompting England to secure a rival partnership to protect its interests. The alliance was further solidified by the Treaty of Tagilde, which is also commemorated as a foundational moment in this historic relationship.
The roots of this cooperation stretch back even further to the Reconquista, when English crusading knights assisted in capturing Lisbon from the Moors. These soldiers were granted land, which encouraged early English settlement and established long-term trade routes. By 1385, the military connection was firmly tested at the Battle of Aljubarrota, where English bowmen fought alongside Portuguese troops to secure the nation's independence. This military synergy continued centuries later when Sir Arthur Wellesley, the future Duke of Wellington, commanded Anglo-Portuguese forces against the invading armies of Napoleon.
Beyond the battlefield, the alliance has been sustained by deep commercial ties. The city of Porto, which lent its name to the famous port wine, remains a hub for British merchant families whose presence highlights the enduring nature of these links. Today, the partnership is celebrated through initiatives like Portugal-UK 650, coordinated by the University of Oxford. This project involves over 50 institutions and aims to promote the values of peace, trust, and friendship that have defined the relationship for over six centuries, ensuring the history remains relevant for new generations.
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Sources
- Summary by Intellect · source: The Fascinating History of England and Portugal's 650 Year Alliance
- Also: Portugal-UK 650 - Jubilee Centre for Character and Virtues
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