The difficulty obtruded itself from the moment the idea was born.  It may be traced back—­so far at least as modern warfare is concerned—­to Sir Francis Drake’s famous appreciation in the year of the Armada.  This memorable despatch was written when an acute difference of opinion had arisen as to whether it were better to hold our fleet back in home waters or to send it forward to the coast of Spain.  The enemy’s objective was very uncertain.  We could not tell whether the blow was to fall in the Channel or Ireland or Scotland, and the situation was complicated by a Spanish army of invasion ready to cross from the Flemish coast, and the possibility of combined action by the Guises from France.  Drake was for solving the problem by taking station off the Armada’s port of departure, and fully aware of the risk such a move entailed, he fortified his purely strategical reasons with moral considerations of the highest moment.  But the Government was unconvinced, not as is usually assumed out of sheer pusillanimity and lack of strategical insight, but because the chances of Drake’s missing contact were too great if the Armada should sail before our own fleet could get into position.

Our third elementary principle is the idea of concentration of effort, and the third characteristic of naval warfare which clashes with it is that over and above the duty of winning battles, fleets are charged with the duty of protecting commerce.  In land warfare, at least since laying waste an undefended part of your enemy’s country ceased to be a recognised strategical operation, there is no corresponding deflection of purely military operations.  It is idle for purists to tell us that the deflection of commerce protection should not be permitted to turn us from our main purpose.  We have to do with the hard facts of war, and experience tells us that for economic reasons alone, apart from the pressure of public opinion, no one has ever found it possible to ignore the deflection entirely.  So vital indeed is financial vigour in war, that more often than not the maintenance of the flow of trade has been felt as a paramount consideration.  Even in the best days of our Dutch wars, when the whole plan was based on ignoring the enemy’s commerce as an objective, we found ourselves at times forced to protect our own trade with seriously disturbing results.

Nor is it more profitable to declare that the only sound way to protect your commerce is to destroy the enemy’s fleet.  As an enunciation of a principle it is a truism—­no one would dispute it.  As a canon of practical strategy, it is untrue; for here our first deflection again asserts itself.  What are you to do if the enemy refuses to permit you to destroy his fleets?  You cannot leave your trade exposed to squadronal or cruiser raids while you await your opportunity, and the more you concentrate your force and efforts to secure the desired decision, the more you will expose your trade to sporadic attack.