Yet during Cromwell's rule the country, notwithstanding all the
restrictions imposed by a stern military government, grew and
prospered. The English forces gained victories by land and sea, and
made the name of the Protector respected as that of Charles I had
never been.
At this period the carrying trade of the world, by sea, had fallen
into the hands of the Dutch, and Amsterdam had become a more important
center of exchange than London. The Commonwealth passed a measure
called the "Navigation Act"[2] (1651) to encourage British commerce.
It prohibited the importation or exportation of any goods into England
or its colonies in Dutch or other foreign vessels.
[2] The Navigation Act was renewed later. Though aimed at the Dutch,
this measure damaged the export trade of the American colonies for a
time.
Later, war with the Dutch broke out partly on account of questions of
trade, and partly because Royalist plotters found protection in
Holland. Then Cromwell created such a navy as the country had never
before possessed. Under the command of Admiral Blake, "the sea king,"
and Admiral Monk, the Dutch were finally beaten so thoroughly (1653)
that they bound themselves to ever after salute the English flag
wherever they should meet it on the seas. A war undertaken in
alliance with France against Spain was equally successful. Jamaica
was taken as a permanent possession by the British fleet, and France,
in return for Cromwell's assistance, reluctantly gave the town of
Dunkirk to England (1658), and the flag of the English Commonwealth
was planted on the French coast. But a few years later (1662), the
selfish and profligate Charles II sold Dunkirk back to Louis XIV in
order to get money to waste on his pleasures.