Another legend claims that following the Navigation Act 1651 (an ordinance 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 Battle of Goodwin Sands and the First Anglo-Dutch War.