a decisive action turns back to succour such of his ships as are assailed and thereby renders a decisive action inevitable. There is, moreover, another function to be assigned to the battle-cruiser in a general action, and that is a function which was defined once for all by Nelson himself in the immortal memorandum in which he explained to his captains the mode of attack he proposed to carry out at Trafalgar. "I have," wrote Nelson, "made up my mind to keep the fleet in that position of sailing ... that the order of sailing is to be the order of battle, placing the fleet in two lines of sixteen ships each, with an advanced squadron of eight _of the fastest sailing two-decked ships_ which will always make, if wanted, a line of twenty-four sail, on whichever line the Commander-in-Chief may direct." Owing to the lack of ships this disposition was not adopted on the day of Trafalgar, but the principle involved is not affected by that circumstance. That principle is that a squadron of the fastest sailing ships in the fleet was to be detached from the two fighting lines entrusted with the initial attack, and reserved or "refused" until the development of the main attack had disclosed to the Commander-in-Chief the point at which the impact of this "advanced squadron" would by superior concentration on that point secure that the enemy should there be decisively overpowered. The essence of the matter is that the ships so employed should by virtue of their superior speed be endowed with a tactical mobility sufficient to enable them to discharge the function assigned to them. I need hardly insist on the close analogy which subsists between Nelson's "advanced squadron" and a modern squadron of battle-cruisers similarly employed, and although the conflict of modern warships must needs differ in many essential respects from the conflicts of sailing ships in Nelson's days, yet I think a clear and authoritative exposition of one at least of the uses and functions of the battle-cruiser in a fleet action may still be found in what I have called elsewhere "the last tactical word of the greatest master of sea tactics the world has ever known, the final and flawless disposition of sailing ships marshalled for combat." CHAPTER IX THE DISTRIBUTION AND SUPPLY OF NAVAL FORCE