Admiral Tromp had been cruising up and down the Channel for some weeks on the look-out for the Spaniards, and on September 16 he sighted the armada.
He had only thirteen vessels with him, the larger part of his fleet having been detached to keep watch and ward over Dunkirk.

With a boldness, however, that might have been accounted temerity, Tromp at once attacked the enemy and with such fury that the Spanish fleet sought refuge under the lee of the Downs and anchored at the side of an English squadron under Vice-Admiral Pennington.

Rejoined by seventeen ships from before Dunkirk, the Dutch admiral now contented himself with a vigilant blockade, until further reinforcements could reach him.

Such was the respect with which he had inspired the Spaniards, that no attempt was made to break the blockade; and in the meantime Tromp had sent urgent messages to Holland asking the Prince of Orange and the admiralties to strain every nerve to give him as many additional ships as possible.

The request met with a ready and enthusiastic response.