The Windsor Treaty – Constable Route

The world’s oldest alliance – The Windsor Treaty of 1386

Historic background

Portugal was the first European country where the people – the common people and the bourgeoisie – came to power after the War with the Kingdom of Castile, through Nuno Álvares Pereira, the Constable, and D. João I, the king that started a new dynasty.

Thanks to that, the world’s oldest alliance –  which began in 1372 with the Treaty of Tagilde in Vizela and was confirmed in  the following year with the signing of the Treaty of Peace, Amity and Alliance, sealed at St Paul’s Cathedral in London.

In 1386, the Treaty of Windsor confirms the oldest alliance in the world.


Current locations covered by the Route (with colored markers) and possible future locations (grey markers):


In the Military Field of São Jorge, on August 14th, 1385, Portugal won the decisive victory over Castile in the Battle of Aljubarrota