"Such was that bloody Battle of the Four Days, or Straits of Calais, the most memorable sea-fight of modern days; not, indeed, by its results, but by the aspect of its different phases; by the fury of the combatants; by the boldness and skill of the leaders; and by the new character which it gave to sea warfare. More than any other this fight marks clearly the passage from former methods to the tactics of the end of the seventeenth century. For the first time we can follow, as though traced upon a plan, the principal movements of the contending fleets. It seems quite clear that to the Dutch as well as to the British have been given a tactical book and a code of signals; or, at the least, written instructions, extensive and precise, to serve instead of such a code. We feel that each admiral now has his squadron in hand, and that even the commander-in-chief disposes at his will, during the fight, of the various subdivisions of his fleet. Compare this action with those of 1652, and one plain fact stares you in the face,--that between the two dates naval tactics have undergone a revolution. "Such were the changes that distinguish the war of 1665 from that of 1652. As in the latter epoch, the admiral still thinks the weather-gage an advantage for his fleet; but it is no longer, from the tactical point of view, the principal, we might almost say the sole, preoccupation. Now he wishes above all to keep his fleet in good order and compact as long as possible, so as to keep the power of _combining_, during the action, the movements of the different squadrons. Look at Ruyter, at the end of the Four Days' Fight; with great difficulty he has kept to windward of the English fleet, yet he does not hesitate to sacrifice this advantage in order to unite the two parts of his fleet, which are separated by the enemy. If at the later fight off the North Foreland great intervals exist between the Dutch squadrons, if the rear afterward continues to withdraw from the centre, Ruyter deplores such a fault as the chief cause of his defeat. He so deplores it in his official report; he even accuses Tromp [who was his personal enemy] of treason or cowardice,--an unjust accusation, but which none the less shows the enormous importance thenceforth attached, during action, to the reunion of the fleet into a whole strictly and regularly maintained."[37] This commentary is justified in so far as it points out general aims and tendencies; but the results were not as complete as might be inferred from it.