Treaty of Windsor 1386
Overview
 
The Treaty of Windsor is the oldest diplomatic alliance in the world which is still in force. The Anglo-Portuguese Alliance
Anglo-Portuguese Alliance
The Anglo-Portuguese Alliance, ratified at the Treaty of Windsor in 1386, between England and Portugal is claimed to be the oldest alliance in the world which is still in force — with the earliest treaty dating back to the Anglo-Portuguese Treaty of 1373.This alliance, which goes back to the...

 was renewed in 1386 with the Treaty of Windsor
Windsor, Berkshire
Windsor is an affluent suburban town and unparished area in the Royal Borough of Windsor and Maidenhead in Berkshire, England. It is widely known as the site of Windsor Castle, one of the official residences of the British Royal Family....

 and the marriage of King John I of Portugal
John I of Portugal
John I KG , called the Good or of Happy Memory, more rarely and outside Portugal the Bastard, was the tenth King of Portugal and the Algarve and the first to use the title Lord of Ceuta...

 (House of Aviz
House of Aviz
The House of Aviz is a dynasty of kings of Portugal. In 1385, the Interregnum of the 1383-1385 crisis ended with the acclamation of the Master of the Order of Aviz, John, natural son of king Peter I and Dona Teresa Lourenço as king...

) with Philippa of Lancaster
Philippa of Lancaster
Philippa of Lancaster, LG was a Queen consort of Portugal. Born into the royal family of England, her marriage with King John I secured the Anglo-Portuguese Alliance and produced several famous children who became known as the "Illustrious Generation" in Portugal...

, daughter of John of Gaunt, 1st Duke of Lancaster
John of Gaunt, 1st Duke of Lancaster
John of Gaunt, 1st Duke of Lancaster , KG was a member of the House of Plantagenet, the third surviving son of King Edward III of England and Philippa of Hainault...

. With the victory at the Battle of Aljubarrota
Battle of Aljubarrota
The Battle of Aljubarrota was a battle fought between the Kingdom of Portugal and the Crown of Castile on 14 August 1385. Forces commanded by King John I of Portugal and his general Nuno Álvares Pereira, with the support of English allies, opposed the army of King John I of Castile with its...

, John I was recognized as the undisputed King of Portugal, putting an end to the interregnum
Interregnum
An interregnum is a period of discontinuity or "gap" in a government, organization, or social order...

and anarchy of the 1383–1385 Crisis
1383–1385 Crisis
The 1383–1385 Crisis was a period of civil war in Portuguese history that began with the death of King Ferdinand I of Portugal, who left no male heirs, and ended with the accession to the throne of King John I in 1385, in the wake of the Battle of Aljubarrota.In Portugal, this period is also known...

. Recognition from Castile
Crown of Castile
The Crown of Castile was a medieval and modern state in the Iberian Peninsula that formed in 1230 as a result of the third and definitive union of the crowns and parliaments of the kingdoms of Castile and León upon the accession of the then King Ferdinand III of Castile to the vacant Leonese throne...

 would arrive only in 1411, with the signature of the Treaty of Ayllón
Treaty of Ayllón
The Treaty of Ayllón was a peace treaty signed between the Kingdom of Portugal and Crown of Castile in 1411....

.
 
x
OK