De Ruyter at once gave proof of his skill by bringing back
safely the East Indiamen from Bergen, though a severe storm caused some
losses, both to the fleet and the convoy. The damage was however by the
energy of De Witt and the admiral quickly repaired; and De Ruyter again
sailed out at the beginning of October to seek the English fleet. He
cruised in the Channel and off the mouth of the Thames, but no enemy
vessels were to be seen; and at the end of the month fresh storms
brought the naval campaign of 1665 to a close, on the whole to the
advantage of the English.

Nor were the misfortunes of the Dutch confined to maritime warfare.
Between England and Holland indeed the war was entirely a sea affair,
neither of them possessing an army strong enough to land on the enemy's
coast with any hope of success; but the United Provinces were
particularly vulnerable on their eastern frontier, and Charles II
concluded an alliance with the Bishop of Muenster, who had a grievance
against the States on account of a disputed border-territory, the
lordship of Borkelo. Subsidised by England, the bishop accordingly at
the head of 18,000 men (September, 1665) overran a considerable part of
Drente and Overyssel and laid it waste. There was at first no organised
force to oppose him. It had been the policy of Holland to cut down the
army, and the other provinces were not unwilling to follow her example.
No field-marshal had been appointed to succeed Brederode; there was no
army of the Union under a captain-general, but seven small provincial
armies without a military head. Some thousands of fresh troops were now
raised and munitions of war collected, but to whom should the chief
command be given? William Frederick was dead (October 31, 1664) and had
been succeeded by his youthful son, Henry Casimir, in the Stadholderate
of Friesland. Joan Maurice of Nassau had withdrawn from the Netherlands
and was Governor of Cleves in the service of Brandenburg. He was however
persuaded to place himself at the head of the army, though complaining
bitterly of the inadequacy of the forces placed at his disposal. De
Witt, however, had not been idle. He secured the assistance of
Brunswick-Lueneburg, and an army of 12,000 Brunswickers under the command
of George Frederick von Waldeck attacked Muenster; while a force of 6000
French likewise, under the terms of the treaty of 1662, advanced to the
help of the Dutch. Threatened also by Brandenburg, the bishop was
c