Who was John I's main ally during the war with Castile?
France
England
Aragon
Navarre
Answer
England was John I of Portugal's main ally during the war with Castile. The alliance was solidified through John's marriage to Philippa of Lancaster, and English support played a crucial role in Portugal's victory.
Unraveling the Reign of John I of Portugal: The Pioneering Monarch of the House of Aviz