Which country did John I primarily fight against to preserve Portugal's independence?
Castile
England
France
Aragon
Answer
John I primarily fought against Castile to preserve Portugal's independence. His victory in the succession war with Castile allowed him to establish the House of Aviz on the Portuguese throne and focus on overseas expansion.
Unraveling the Reign of John I of Portugal: The Pioneering Monarch of the House of Aviz