Today in History, May 9, 1386:
A Treaty of Alliance is ratified at Windsor between King Richard II of England and King John I of Portugal.
The Treaty is the longest alliance still in effect. It came about because the Portuguese needed military assistance in defense against their neighbor Castile (Spain) and England needed the Naval assistance of Portugal against France. Portugal’s sea power was at that time stronger than that of the English.
The treaty was strengthened by the marriage of John I of Portugal to Philippa, daughter of the Duke of Lancaster.
The Alliance was again called upon to thwart a Spanish invasion of Portugal in the 1760’s, to fend off Napoleon in the early 19th century, then in WWII when Portugal provided intel and air bases in the Azores to England and America. Air patrols from the Azores were important in the Battle of the Atlantic. The air bases were again provided to England during the Falkland Islands War.