Action of 18 September 1639

This battle took place between 17 and 19 September 1639 when a Dutch squadron under Admiral Maarten Tromp and Admiral Witte Corneliszoon de With, met with a much larger but poorly led Spanish fleet under Antonio D'Oquendo, consisting of 40 to 45 men–of–war and 40 to 50 transport vessels filled with some 13,000 Spanish soldiers who were being transported to Dunkirk.  Tromp with 12 ships spotted the Spanish fleet on the 16th, but waited for de With to arrive with five more ships before attacking.  Despite his numerical inferiority Tromp got the upper hand in a running fight which lasted into the night.  The next day, Zeeland Commodore Joost Banckert, arrived to reinforce the Dutch with 12 more ships.  Fighting continued until the Dutch ran out of gunpowder when D'Oquendo retreated to the roadstead of the Downs hoping on English protection which would eventually lead to the Battle of the Downs, where D'Oquendo was decisively defeated and this marked the end of Spanish seapower.

This fight is notable because Tromp used the line of battle for the first time.