Treaty of Windsor (1386)
The Treaty of Windsor is the diplomatic alliance signed between Portugal and England on 9 May 1386 at Windsor and sealed by the marriage of King John I of Portugal (House of Aviz) to Philippa of Lancaster, daughter of John of Gaunt, 1st Duke of Lancaster. With the victory at the Battle of Aljubarrota, John I was recognized as the undisputed King of Portugal, putting an end to the interregnum of the 1383–1385 Crisis. The Treaty of Windsor established a pact of mutual support between the countries. This document is preserved at the Portuguese National Archives.
- "Tratado de paz, amizade e confederação entre D. João I e Eduardo II, rei de Inglaterra, denominado Tratado de Windsor" (in Portuguese). Portuguese National Archives Digital Collection. Retrieved 4 January 2013.
- Winslett, Matthew (2008). The Nadir of Alliance: The British Ultimatum of 1890 and Its Place in Anglo-Portuguese Relations, 1147--1945. ProQuest. p. 3.