Have a look at this article from the VRT website => Flanders National Day : Why does Flanders celebrate the Battle of the Golden Spurs?

This article contains some serious historical mistakes - which is surprising considering the increasingly strong nationalist/separatist movement in Flanders.

Quote Originally Posted by VRT
The Flemish victory prevented the incorporation of Flanders into the kingdom of France and allowed Flanders to continue to develop as an independent entity.
This is doubly false. Flanders already belonged to the Kingdom of France since 843, well before the Battle of the Golden Spurs in 1302.

The battle was historic because it is the first time that a non professional army (read peasants and burghers) defeated professional knights. However, it did NOT allow the County of Flanders to gain its independence. The King of France came back the next year and crushed the Flemish rebels, and Flanders remained part of France.

Flanders was the first county to be established in the Netherlands. Later the Duchy of Brabant and other fiefdoms were to follow.
This is debatable. It only depends if we mean strictly speaking "county" or also other sovereign state (e.g. duchy). The Duchy of Brabant was a subdivision of the Duchy of Lower Lotharingia, itself divided from the Kingdom of Lotharingia, founded by Lothar I (the eldest grandson of Charlemagne) in 843. The first Count of Flanders, Baldwin I, ruled from 864. He became a vassal of the King of France by marrying Judith, daughter of Charles II of France.

The Flemish cities thrived on the flourishing cloth trade and attracted the attention of the French kings, who wanted to expand their territory.
Why would they want to expand their territory while Flanders was already part of France ? The reason for the Battle of the Golden Spurs was than the Flemings massacred the Royal garrison in Bruges and refused to pay taxes to the King of France.

The army of Flemish burgers and peasants and subsequent battles prevented the annexation of Flanders by the kingdom of France allowing Flanders and Belgium to continue to develop as independent entities.
False again, as explained above. As for "Belgium", it was not unified until 1792 under French rule. In the late 15th century, Flanders, Hainaut, Brabant and Luxembourg all passed to the Habsburgs by marriage, while the big Principality of Liege remained the only truly independent German state in what is now Belgium.

What is now called "Flanders" has little to do with the historical County of Flanders. The county inlcuded only 2 of the 5 Belgian provinces in Flanders, but also comprised French Flanders (the northern half of the departement du Nord in France, i.e. the region of Lille and Dunkirk). The rest of the modern Flemish region was part of the Duchy of Brabant (partly Francophone), and the Principality of Liege (mostly Francophone).

In fact, even the County of Flanders was not ruled by Flemings since 1127, when it passed to the House of Normandy, then 1191 when it was united with the County of Hainaut. After that it was ruled by the Dampierre (from Champagne) and the Dukes of Burgundy, before passing to the Habsburgs. So the County of Flanders was never independent, and ruled mostly by French nobility through its history.

The Battle of the Golden Spurs was a military feat, but had no political consequence, and no relation to an independent Flanders. It was just a bloody massacre that followed another one (the Bruges Matins). Not much to be proud of...

I have nothing against Flanders getting more autonomy, even its independence. But I don't think that choosing the anniversary of the Battle of the Golden Spurs as the "National Day" has any meaning - except if the Flemings want to give an image of butchery and failure to gain their independence after all.

When I see Flemish flags in Brussels and Flemish people outside the provinces of East and West Flanders getting all excited about 11 July and the Golden Spurs, I wonder if they understand history at all. What does a Brabantine or Limburgs have to do with that battle ? They were not even part of France, but of the Holy Roman Empire !