Since the 9th century the County of Flanders, born out of the remnants of the empire of Charlemagne and his sons, had been independent. In 1300 however, a reconsolidated French Kingdom under Philip IV the Fair annexed Flanders, and its Count, Guy of Dampierre, and his two sons were taken hostage. The French King had been angered by an alliance between Count Guy and the English King, Edward I. In Guys place Philip IV appointed a governor, Jacques de Châtillon. This act, an ill-received visit by the King in 1301 and newly imposed (high) taxes, caused widespread unrest, and on May 28, 1302 the bomb burst in Bruges, the key historical Flemish city, when every Frenchman the Bruges citizens could lay their hands on was murdered. This event is called "de Brugse Metten", and it is from this phrase that the Flemish expression "korte metten maken" (meaning a rapid and lasting "cleanup") is derived.
Enraged and humiliated, the French King sent a powerful Knight's army under Count Robert II of Artois. Historical accounts of that period are contradictory, but generally it is assumed that it was 8,500 strong, consisting a.o. of 2,500 fully armored knights, 1,000 crossbowmen and 2,000 pikemen, with the remainder being infantry. To counter this threat, the Flemings hastily assembled an army of their own, made up almost completely of town militia and ultimately some 9,000 strong. Three prominent leaders were a son and a grandson of the imprisoned Count of Flanders, Guy of Namur and Willem van Gulik respectively, and Pieter de Coninc, a leader of the Bruges uprising. Others were Jan Borluut, at the head of the 700-strong Ghent contingent, and Jan Breydel. While the French army was a professional, heavily armed and armored force, the Flemish army was an ad hoc formation, relatively lightly armed and without experience. Numbering only some 400 nobles, it was basically a light infantry army.
At noon on July 11, 1302, a hot summer day, the two armies clashed in an open field called the "Groeningekouter",just west of the Flemish city of Kortrijk on the Leie river (in Anglosaxon countries referred to a Courtrai, on the Lys river). The Flemings took position behind some brooks criscrossing the field, with their backs to the city walls. They organised themselves in three wings, the men from East Flanders on the right, those from Bruges to the left, and in the centre mostly men from West Flanders. Inside Kortrijk there was actually a small French garrison, so technically speaking the Flemish Army was surrounded, but the French inside the city walls were kept at bay by men from Ieper (in Anglosaxon countries known as Ypres) and a reserve force of 500 under Jan Van Renesse, from Zeeuws-Vlaanderen. During the battle they did in fact try to intervene, but were quickly chased back.
Probably the biggest mistake of the French commander, Robert of Artois, was not to allow his crossbowmen to destroy the Flemish army from a distance. Possibly in utter disdain for what he considered a peasant's army, he prematurely urged his knights to charge across the wetlands. This proved to be their doom. The French left wing had to get over the broadest stream, the Grote Beek, three meters wide. Once across, the knights had lost their impetus, were quickly knocked from their steeds, and killed with the dreaded hellebaarden en goedendags. On the right side (from the French point of view) it was the same scenario. Only in the centre, where the French cavalry had been able to gain speed and momentum over a longer stretch, were the attackers able to penetrate deeply. But then Jan van Renesses reserves intervened and here, too, the French suffered huge losses and were thrown back. The drawing above is a romanticized depiction where one can make out, in the background, a line of charging French knights, while in the foreground Flemish infantry armed with peaks are bracing. Between the two forces one can discern a brook. The picture is also correct in that the Flemish Lion on the shoulder "patch" is the version of that time, not so different from the Lion assumed by a Flemish Count during a crusade.
When evening came, the pitiful remnants of one of the most splendid French Knights armies ever withdrew in disorder to Doornik, 25 kilometres to the south. For a long time they were chased by the victorious Flemings. So numerous were the French casualties, which included the commander, Robert of Artois, that the battlefield was littered with the knights' golden spurs, and this is how the battle got its name.
The Guldensporenslag proved that knights could be defeated by disciplined infantry. The political consequence was that Flanders was temporarily independent again. True, a large follow up battle in 1304, at Mons-en-Pévèle, ended undecided and the aftermath thereof forced the Flemings to accept unfavourable conditions. But without Kortrijk 1302, Flanders would be a part of France today. In the east in 1285, Duke Jan I of Brabant had won against a German army in Woeringen, near Cologne. The 1302 victory in Kortrijk, in the west, ensured that Flemish would be spoken in an arc ranging from the coast till the border with the German empire. July 11, 1302, is thus rightly the Official Holiday of the Flemish Region.