Tromp attacked Blake, and a group of ships with him that were protecting his ship, the Triumph. This was in the opening moves of the battle. At first light on the first day, Tromp could see two groups of ships to his South. due South, he could see a group of a dozen or so ships, with William Penn's flag on one. Two miles to the East, was another group of similar size, with John Lawson in command.
In between were a half dozen ships. One was the Triumph, with Robert Blake and Richard Deane jointly in command. The rest of the English fleet was 5 or 6 miles to the leeward. The wind was from the Northwest. The Dutch charged directly downwind. Jan Evertsen went for Lawson, Tromp went for Blake, Pieter Florissen tried to go into the gap between Blake and Penn. De Ruijter charged directly at Penn. Lawson intended to tack to the West and sail South of Blake. He intended to then tack back towards Blake and attack from the Southwest. Penn tacked back towards Blake, having been on a Westerly course, at the start.
As I said, De Ruijter charged into Penn's group of ships. They boarded the Assistance, the Prosperous, the Oak, and the Sampson was sunk. The Assistance was John Bourne's flagship. He was Rear-Admiral of the Blue. The Sampson was a Dutch prize (the Sampson van Hoorn, captured while on fishery protection duties in July 1652, off the East coast. The Oak was also a Dutch prize (evidently an Akerboom, perhaps merchant).
Unfortunately for De Ruijter and the Dutch, John Lawson now arrived and recaptured the Assistance, Prosperous, and Oak. They also broke through the circle of Dutch ships around Blake, and broke the Dutch attack.
This first encounter happened right South of Portland Bill. Blake had started his voyage from Beachy Head, and tacked down the Channel, mostly against the wind. By the morning of the first day, the wind had shifted to the Northwest.
As darkness fell on the first day, the Dutch withdrew to the North, to cover their convoy from attacks by Monck's frigates. In the course of the first day's battle, Jan Evertsen's squadron had suffered dearly. He lost 8 ships. Four were sunk: the ship of Captain Cleydyck (Kleijdijck) (30 guns); the Kroon Imperiaal (34 guns), the ship of Cornelis Janszoon Poort; the Engel Gabriel (36 guns), the ship of Isaak Sweers; the Arche Troijane (28 guns), the ship of Abraham van Campen, and probably Sipke Fockes' ship, which was apparently called the Groote Sint Lucas (28 guns).
Schelte Wichelma's ship, the Frisia, blew up. Almost all of the ships that blew up in the Anglo-Dutch wars were probably caused by in sufficient care when handling gun powder. Another possible cause is that a ship can catch fire, and blow up. Apparently, it was possible to have a lot of powder dust in the air, that could be explosive, if there was a spark. It is almost impossible for a hit by a single shot to cause a ship to explode (like the battlecruisers at Jutland or the Hood in 1941).
Three more were captured: the Wapen van Holland (30 guns), commanded by Hendrick de Munnich; the East Indiaman, the Vogelstruis (40 guns), commanded by Cornelis Adriaanszoon Cruijck; and Cornelis Loncke's ship, the Faam (30 guns).
That was all by the end of the first day.
At the end of the third day, there were about 35 Dutch ships protecting the convoy, fighting to keep the marauding English frigates away. Two Dutch warships were lost on that last day: the Vergulde Haan (36 guns) and the Groote Liefde (38 guns).