1259



- September - The Empire of Nicaea defeats the Principality of Achaea at the Battle of Pelagonia, ensuring the eventual reconquest of Constantinople in 1261.

- December 4 - Kings Louis IX of France and Henry III of England agree to the Treaty of Paris, in which Henry renounces his claims to French-controlled territory on continental Europe (including Normandy) in exchange for Louis withdrawing his support for English rebels.