On the 29th of July, 1018, the Battle of Vlaardingen was fought. The German emperor sent an army towards western Frisia to subdue the rebellious Count Dirk III.
However, the imperial army was defeated by the Vlaardingers and fled in panic.
This is an interesting event because a superpower of the time was vanquished by a – theoretically – weaker opponent. Also, it is an important milestone in the development and the independence of the county of Holland.
Despite the fact that it was a spectacular and prominent feat of arms, the Battle of Vlaardingen is not very well known, even among the Dutch.
A large imperial army, made up of troops supplied by the various bishops of region, under the command of Godfrey II, Duke of Lower Lorraine, then headed for the stronghold at Vlaardingen. The ensuing Battle of Vlaardingen was a disaster for the imperial army and a tremendous victory for Count Dirk; many of the imperial commanders perished and Duke Godfrey was captured. Following this victory, Dirk III was permitted to keep his lands and he continued levying tolls.
Later on, Dirk also managed to acquire more lands east of his previous domains at the expense of the Bishop of Utrecht. After the death of Emperor Henry II in 1024, Dirk supported Conrad II for the succession to the kingship.
After Count Dirk III’s death in 1039, imperial armies were sent on a few more occasions seeking to reclaim the lands held by the Frisian counts. The powerful Robert I, Count of Flanders (called Robert the Frisian) helped Dirk V, grandson of Dirk III and his own stepson, to restore Frisia to the counts.