The English commanders were Generals at Sea George Monck and Richard Deane, with Admirals John Lawson and William Penn, the second of whom would later father the founder of Pennsylvania. Their fleet was big and gun-heavy. English doctrine, hammered out earlier that year after the loss at Dungeness and the recovery at Portland, called for ships to fight in line, holding station so that each could fire its broadside without fouling its neighbour. Heavy ordnance, accurate fire, musketry sweeping the upper deck to kill officers, then if necessary a boarding party. Maarten Tromp's Dutch were organised the opposite way. Lighter ships, more crew per gun, a much higher proportion of soldiers, and a fondness for fireships to finish off cripples. Tromp himself was the most celebrated seaman in Europe, the man who had broken a Spanish Armada in the Downs in 1639. His instinct was to concentrate, mass, swarm. He was sailing into a trap his own tactical history had built.

The Dutch came in with the weather gauge. Tromp tried to break the English line and get among them for a boarding fight. The English ships held their formation. Witte de With, Tromp's vice-admiral, hit the centre of the English line. Lawson met him. The broadsides went in. Dutch hulls, lighter built and lighter armed, took the worst of it. Tromp tried again later in the day with a concentrated rush. Same result. By nightfall two Dutch ships had been lost outright and many more were too damaged to fight effectively. None of the English ships had been sunk or taken. Tromp drew off to consult his captains and count his powder. He had almost none left.

Robert Blake, the third of the three Generals at Sea and recovering from wounds taken at Portland, came up on the morning of 3 June with a fresh squadron of eighteen ships. Tromp now faced an enemy who outnumbered him, outgunned him, and held the line. He attacked anyway. He had little choice; running would mean abandoning the fleet's morale and the merchant convoys that depended on the navy's protection. Then the wind dropped. Sails hung slack. Dutch ships sat motionless within range of English long guns and could not return fire effectively because their powder was almost gone. The English worked their guns methodically. The Dutch line came apart. When a breeze finally returned, the Dutch were running and the English chased them deep into the evening, scooping up cripples. The final tally was eleven Dutch ships captured, nine destroyed, twenty in all. The only senior English loss was Richard Deane, who had been killed beside Monck on his quarterdeck by a chain shot fired in the first hour of fighting on day one. Monck reportedly took off his coat, draped it over Deane's body, and kept giving orders.

The Battle of the Gabbard was the first decisive naval action of the gunpowder age won by the line of battle. The doctrine that the English Generals at Sea had been writing into Fighting Instructions over the previous year proved itself here against the best fleet in the world. Other navies took notes. By the end of the seventeenth century the line of battle had become orthodoxy on every European fleet, the standard against which a captain was judged. The architecture of warships followed. Ships of the line, built specifically to stand in formation and trade broadsides, dominated naval construction for the next two centuries. The wooden walls that beat Napoleon at Trafalgar were direct descendants of the formation that Monck and Deane held off the Gabbard.

The English exploited the victory hard. Blake imposed a blockade of the Dutch coast that strangled the Republic's overseas trade and crippled its merchants. The fleets met again seven weeks later at the Battle of Scheveningen, off the Dutch coast, in late July 1653. Tromp was killed in the opening exchanges, struck through the chest by a musket ball, and the war moved swiftly toward an English-imposed peace. Reports of the Gabbard victory were read aloud in London with what one chronicler called 'great exclamation', the first major naval success England had had since the days of Elizabeth I. The Restoration would later overshadow the Commonwealth's military reputation, but the navy that defeated Napoleon was built on tactics first proven off a Suffolk shoal on a thin June afternoon.