The effect of prolonged peace has been to make "concentration" a kind of shibboleth, so that the division of a fleet tends almost to be regarded as a sure mark of bad leadership. Critics have come to lose sight of the old war experience, that without division no strategical combinations are possible. In truth they must be founded on division. Division is bad only when it is pushed beyond the limits of well-knit deployment. It is theoretically wrong to place a section of the fleet in such a position that it may be prevented from falling back on its strategical centre when it is encountered by a superior force. Such retreats of course can never be made certain; they will always depend in some measure on the skill and resource of the opposing commanders, and on the chances of weather: but risks must be taken. If we risk nothing, we shall seldom perform anything. The great leader is the man who can measure rightly to what breadth of deployment he can stretch his concentration. This power of bold and sure adjustment between cohesion and reach is indeed a supreme test of that judgment which in the conduct of war takes the place of strategical theory. In British naval history examples of faulty division are hard to find. The case most commonly cited is an early one. It occurred in 1666 during the second Dutch war. Monk and Rupert were in command of the main fleet, which from its mobilisation bases in the Thames and at Spithead had concentrated in the Downs. There they were awaiting De Ruyter's putting to sea in a position from which they could deal with him whether his object was an attack on the Thames or to join hands with the French. In this position a rumour reached them that the Toulon squadron was on its way to the Channel to co-operate with the Dutch. Upon this false intelligence the fleet was divided, and Rupert went back to Portsmouth to cover that position in case it might be the French objective. De Ruyter at once put to sea with a fleet greatly superior to Monk's division. Monk, however, taking advantage of thick weather that had supervened, surprised him at anchor, and believing he had a sufficient tactical advantage attacked him impetuously. Meanwhile the real situation became known. There was no French fleet, and Rupert was recalled. He succeeded in rejoining Monk after his action with De Ruyter had lasted three days. In the course of it Monk had been very severely handled and forced to retreat to the Thames, and it was generally believed that it was only the belated arrival of Rupert that saved us from a real disaster.