French Community of Belgium celebrates today.

It might be somewhat complicated to keep up with Belgium's official (federal and regional) holidays:  the national one on July 21, the Flemish one on July 11, the German-speaking community day on November 15. 
The French Community celebrates today, September 27. This day is chosen because the Dutch army under the command of the son of William of Orange, withdrew its troops from Brussels on September 27, 1830. 
http://www.federation-wallonie-bruxelles.be/index.php?id=440&L=1
http://en.wikipedia.org/wiki/French_Community_of_Belgium