As a result of a trade dispute, Emperor Henry II sent an army towards West Frisia to subdue the rebellious Count Dirk III.
Frisia, the most peripheral part of the duchy, fell under the office of Adalbold, bishop of Utrecht, and under Dirk III, to whom the coastal defence in the west had been delegated.
Henry assigned Adelbold and Duke Godfrey to organise a punitive expedition against the rebellious Count Dirk, who then left the meeting, announcing his intent to foil the imperial plans.
Three more bishops would supply troops: Baldrick II of Liège, Gerhard of Cambrai, and the Archbishop Heribert of Cologne.
This turned out to be a bad omen, because on the way downriver with the Imperial fleet from Tiel to Vlaardingen the bishop fell ill. At Heerewaarden he left his ship and died on the very day of the battle.
The settlement of Vlaardingen in this period consisted of only seventeen wooden houses, capable of providing a militia of at best fifty men.
To send out a host of three thousand men would therefore have been a definite overkill, equalling the known total size of the standing forces of the four bishoprics involved.
Initially, Godfrey lined his men up around the castle, but then he ordered them to march towards a flat field, because it would be difficult to cross the ditches that were dug all over the place.
Duke Godfrey was released promptly, and he arranged a reconciliation between Bishop Adelbold and Count Dirk III.
The early medieval chronicles do not make clear exactly where in Vlaardingen the events took place or which manoeuvres the forces made.
From this spot one has a view over the Merwede, the port, the count's farmstead and the surrounding area, making it a strategic position.
It is tempting to regard this discovery as the remains of a ring castle, of the motte-and-bailey type, built around the year 1000 by Count Dirk III.
After 1150, Count Floris III established a toll in Dordrecht, and gradually it became the major town in the county of Holland.
The origin of this misconception lies in the Rymchronyk: a famous forgery, attributed to a Klaas Kolyn, a monk from Egmond Abbey who allegedly had put the history of Holland into verse in the 12th century.
It says, among many other things, that Dirk III founded a fortification and a village along the Merwede, that he named the settlement 'Dordrecht', and that the famous battle in 1018 was fought on that location.
The Battle of Vlaardingen can be considered as the starting point for a greater de facto autonomy of the later County of Holland.
Later in the 11th century, German kings and emperors, and the bishops of Utrecht, made further attempts to subdue the counts of West Frisia.
They almost succeeded when Duke Godfrey 'the Hunchback' and Bishop William drove the young Count Dirk V out of Frisia.
In the summer of 2018, the First Battle of Vlaardingen was commemorated with a historical reenactment in the Broekpolder recreational area on the north-west side of the town.