The manoeuvre of doubling an enemy's line of battle consists in sending ships round by either of its extremities for the purpose of placing some of those in that line, between two fires. In order to double a fleet, the ships should advance beyond its van, or fall in its rear, when by tacking or veering according as they are to leeward or windward of the line, they may get into the required position on its opposite side. It is right to observe, however, that this manoeuvre ought to be attempted under favourable circumstances only, as the doubling ships are liable to be separated so far from their own fleet as to be prevented from rejoining it ; and it is, on the whole, considered more advantageous to double a fleet by its rear than by its van, since in the event of some of the enemy's ships being damaged, and unable to keep up with the rest, such ships may be taken by those which are performing the manoeuvre of doubling : should any of these last be separated from their fleet, they can remain in the rear without risk, till an opportunity is offered of rejoining it. At the battle of the Nile (1798), Admiral Nelson doubled the van of the French line, and attacked it on both sides, while tho other ships of that line, the whole fleet being at anchor, could afford no assistance. Iu order to avoid being turned, the largest ships of a fleet ought to bo in the van and rear of its line when in order of battle ; and the rate of sailing for each should be such that the rear ships may never be astern of the enemy. Care should also be taken that the ships are as close together as possible, that the enemy may not pass between any two of them, and thus break the order of battle.
It is well known, from the records of naval history, that the manceuvro of cutting through the line of an enemy's fleet during an engagement has been several times performed by English commanders since the middle of the 17th century. In an action with the Dutch, in the year 1652, Sir George Ayscue is said to have charged from the leeward through the fleet of the enemy; and in that between the English and Dutch fleets in 1665, the earl of Sandwich cut through the centre of the Dutch line, and caused the disorder which ended in its total defeat : again in May, 1672, Sir Joseph Jordan, of the Blue squadron, having the advantage of the wind, pierced the Dutch fleet and threw it into confusion. But the action which first gave notoriety to the manoeuvre was that in which Admiral Rodney gained the im portant victory over the French fleet commanded by the Comte do Grasse : this action was fought in 1782. The battle in which the brilliant career of Lord Nelson terminated with a decisive victory (1805) owed the success with which it was crowned to the employment of a like mode of attack.
The honour of having been the first to demonstrate fully the prin ciples on which the manoeuvres of an attack against fleets to windward or to leeward depend, is generally ascribed to Mr. Clerk of Eldin, who
published the first edition of his Essay on Naval Tactics! in 1782; and it has been asserted (Playfair's Memoir of Mr. Clerk ') that Clerk had, in conversation, communicated to Sir Charles Douglas (Rodney's flag-captain) his whole system of tactics in the year preceding that in which the battle with the Comte de Grasse was fought. The accuracy of this assertion has been however disproved by Sir Howard Douglas, in his Memoir on Naval Evolutions ;' and from an account of the circumstances under which the.manceuvre of breaking the French line was performed, as they have been given by Sir Charles Dashwood (one of Admiral Rodney's aides-do-camp on the day of the action), it appears that the idea of the manceuvre was, at the moment, suggested to the admiral by Sir Charles Douglas on perceiving an opening in the French line between two of the ships near its centre. The French fleet wan formed in line on a larboard tack, and tended to gain the windward side of the British line, which from the leeward side advanced obliquely towards the fifth ship from the van of the enemy. Signals were then made for the British ships to close up in their line, and the action com menced as the two fleets ranged in opposite directions alongside of each other. When the centre of the British fleet came opposite the third or fourth ship of the French line, Admniral Rodney's ship began a close action within half a musket-shot against the ships of the enemy with which it came successively abreast ; and then the opening appear ing as above mentioned, the opportunity was seized of passing through it : this was done so near the enemy, that the admiral's ship almost touched the French ship on each side. The ships astern of time admiral followed him closely, and these kept up a powerful raking fire against the ships in the rear division of the enemy's fleet, which, being driven to leeward as the van of the British fleet pawed them, broke into two divisions, and made sail before the wind to escape. As soon as the van of the French fleet was left beyond the rear of the still advancing line of British ships, it also broke into two divisions, which retreated in different directions ; and then the signal being made for the ships to close up. the British fleet followed in pursuit of that division with which the French admiral had retire. At' the battle of Trafalgar 11805). the combined French and Spanish fleets were drawn up in one line, of a crescent form, the convex part being to leeward of the wings, while the fleet of Lord Nelson bore tip against it in two lines, in the order of sailing; the leading ships of the lines broke through the fleet of the enemy in two places, and were followed by those of their respec tive divisions.