In 1838, the Flemish author Hendrik Conscience published the novel De Leeuw van Vlaenderen, of de Slag der Gulden Sporen ("The Lion of Flanders, or the Battle of the Golden Spurs"), which is based on the Battle of the Golden Spurs (Dutch: Guldensporenslag) near Kortrijk on 11 July 1302, and the events leading up to it.
The novel was very significant because its publication "coincided with the emergence of the Flemish Movement which supported an increasingly assertive Flemish political identity" (Wikipedia.) The book's success earned Conscience the epithet of "the man who taught his people to read". Eventually, 11 July became the Day of the Flemish Community.
The French suffered a crushing defeat during the battle and lost a significant part of their nobility, so it would not be surprising if that were reflected (or at least mentioned) somewhere in a French work of literature written before 1838. However, the French Wikipedia article Bataille de Courtrai (1302) does not mention any French works that refer to the battle. So was Conscience's De Leeuw van Vlaanderen really the first work of literature that at least mentions this battle?