Excerpts from Books and Wikipedia
"The battle at Aljubarrota, central Portugal, on August 14, 1385, is seen by the Portuguese as the most important in their history, for it came at a moment when the very existence of Portugal as an independent kingdom was under threat. . . . The struggle became linked to the Hundred Years War: England backed Joao, France backed Juan. . . . Joao won the Portuguese crown, founding the house of Aviz that ruled the country for almost 300 years." [Furtado: 1001 Days]