Then came the news of the circumvallation, and with it alarm.

The Count de Berg was therefore ordered (June 17) at the head of an army of 30,000 foot and 7000 horse to advance into North Brabant and raise the siege.

But the stadholder was prepared and ceaselessly on his guard; and the Spanish general, after several vain attempts, found the Dutch lines unassailable.

With the view of compelling Frederick Henry to follow him, Berg now marched into the heart of the United Provinces, devastating as he went with fire and sword, took Amersfoort and threatened Amsterdam.
But the prince confined himself to despatching a small detached force of observation; and meanwhile a happy stroke, by which a certain Colonel Dieden surprised and captured the important frontier fortress of Wesel, forced the Spaniards to retreat, for Wesel was Berg's depot of supplies and munitions.
While all this was going on the Prince of Orange had been pushing forward the siege operations.

On July 17 the forts of St Isabella and St Anthony were stormed.