In Flanders, nobility was a clearly defined class. However, after many years, the Erlembaldi family had acquired the hereditary castellanship of Brugge and a network of marriage relationships with many Flemish nobles. When Charles, Count of Flanders, wished to break them, he threatened to investigate their servile origins, thus at once challenging their own position and demeaning the noble families into which they had married. This was an unwise move for it provoked them successfully to plot his assassination in 1127. The townsmen of Gent and Brugge played a major part in the resulting civil war, then in the resolution of the succession to Thierry of Alsace.
 

Source: Leo van de Pas