 Complete the following phrase:  Another legend claims that following the Navigation Act 1651 an ordice by Oliver Cromwell requiring all foreign fleets in the North Sea or the Channel to dip their flag in salute the Wilhelmus was sung or rather, shouted by the sailors on the Dutch flagship Brederode in response to the first warning shot fired by an English fleet under Robert Blake, when their captain Maarten Tromp refused to lower his flag. At the end of the song, which coincided with the third and last English warning shot, Tromp fired a full broadside, thereby beginning the 