Editing Four Days' Battle (section)

===Naval tactics===
The introduction of sailing ships with a [[square rig]], of a type later called the ship of the line, which were heavily armed with cannon, brought about a gradual change in naval tactics. Before and during the First Dutch War, fleet encounters were chaotic and consisted of individual ships or squadrons of one side attacking the other, firing from either side as opportunities arose but often relying on capturing enemy ships by boarding. Ships in each squadron were supposed to support those in the same squadron, particularly their flag officer, as their first priority. However, in the melee of battle, ships of the same squadron frequently blocked each other's fields of fire and collisions between them were not uncommon.<ref>Palmer, pp.128-9</ref>

Although Lieutenant-Admiral [[Maarten Tromp]] had formed a line against the Spanish fleet in 1639 in the [[action of 18 September 1639]], this was not a planned formation but a desperate attempt to hold off a greatly superior, but badly organised, enemy. The initial sea battles of the First Dutch War were largely indecisive melees, but later in that war [[Robert Blake (admiral)|Robert Blake]] and [[George Monck, 1st Duke of Albemarle|George Monck]] issued instructions for each squadron to stay in line with its flag officer. At the [[Battle of Portland]] Tromp's attempt to overwhelm the English rear by concentrating his whole fleet against it and using his favourite tactic of boarding was frustrated by the English rear remaining in line ahead<ref>Palmer, pp.131-3</ref> at the [[Battle of the Gabbard]], the English fleet in line ahead forced the Dutch into an artillery duel that defeated their more lightly armed ships with a loss of Dutch 17 ships sunk or captured.<ref>Palmer, pp.134-5</ref>

Between the first and second wars, the Dutch built the "New Navy", some sixty larger ships with heavier armament, about forty cannon, although the shallow waters around the Netherlands prevented them building ships as big as the largest English ones: additionally, English ships of the same size tended to have more and larger guns than their Dutch equivalents.<ref>Fox, pp. 47-8</ref> However, many of those the Dutch built were relatively small convoy escorts, [[frigate]]s by English standards. It was intended to replace these by sixty heavier vessels but not all those planned had been completed or fitted out by the start of the war in 1665.<ref>Bruijn, pp.64-6.</ref> At the time of the Second Dutch War, the English fleet also had a signalling system which, if still rudimentary, was better than the Dutch reliance on standing instructions to fight in line. In the [[Battle of Lowestoft]] and the [[St. James's Day Battle]], the English fighting in line ahead defeated the Dutch who did not.<ref>Palmer, pp.138-9</ref> De Ruyter favoured the tactic of concentrating his attack on a portion of the enemy's line, so achieving a breakthrough, and the capture of ships by boarding.<ref>Bruijn, pp. 64-6</ref> However, in the Four Days' Battle the Dutch generally fought in line, and the English fleet did not do so, at important stages in the fighting.<ref>Palmer, p. 140</ref>

From early in the 17th century, the Dutch navy had used fireships extensively, and in the First Anglo-Dutch War at the [[Battle of Scheveningen]], Dutch fireships burned two English warships and an English fireship burned a Dutch warship. The Dutch in particular increased the number of their fireships after the outbreak of the Second Anglo-Dutch War but, at the [[Battle of Lowestoft]], it was two English fireships that burned six Dutch warships which had collided and become entangled with one another. However, the limitations of fireships when used in open waters was demonstrated during the Four Days' Battle, where many were destroyed while trying to attack well-armed ships able to manoeuvre freely. The surrender of the English {{HMS|Prince Royal|1660|6}} when attacked by several Dutch fireships after it had run aground because of the panic this attack caused only demonstrated that fireships were useful against warships that were stationary or in confined harbours, but not those able to move in the open sea. However, this overall lack of success in this battle did not prevent both sides adding more fireships to their fleets.<ref>Coggeshall, pp. 13-14</ref>