A well-designed defensive will always threaten or conceal an attack.  Unless it does this it will not deflect the enemy’s strategy in our favour.  Thus, in 1756, the French, by assuming the defensive in the Channel, threatened an attack on our coasts, and concealed their attack on Minorca.

This power inherent in the defensive is peculiarly strong in naval warfare, since the mobility of fleets enables them to pass instantaneously from the defensive to the offensive without any warning.  When we assume the defensive because we are too weak for the offensive, we still do not lay aside attack.  The whole strength and essence of the defensive is the counter-stroke.  Its cardinal idea is to force the enemy to attack us in a position where he will expose himself to a counter-stroke.

The stock instance upon which naval defensive is usually condemned is the burning of our ships at Chatham by the Dutch.  But in that case we were not acting on the defensive at all.  We had laid up our battle fleet and were doing nothing.  We were purely passive, in expectation of peace.  It is really an instance of the successful use of defensive by the Dutch.  Being no longer strong enough for a general offensive, they assumed the defensive, and induced us to lay up our ships and so expose ourselves to a counter-stroke.  It was a counterstroke by the worsted belligerent to get better terms of peace.

So far is the defensive from excluding the idea of attack, that it may consist entirely of a series of minor offensive operations.  Clausewitz calls it “a shield of blows.”  It is often called offensive-defensive, or active defence.  Neither term is really necessary.  For a defensive which excludes the idea of offence or action is not war at all-at least at sea.  The old Elizabethan term Preventive most closely expresses the idea.

The most important function of the defensive is that of covering, buttressing, and intensifying the main attack.  No plan of campaign, however strong the offensive intention, is perfect which does not contemplate the use of the defensive.  Without some use of the defensive the cardinal principle of concentration can rarely be fully developed.  To develop the highest possible degree of concentration upon the main object or objective, the defensive must be assumed everywhere else.  Because it is only by using the defensive in the minor or less important theatres of operation that the forces in those theatres can be reduced to the minimum of security, and the maximum of concentration can thereby be obtained in the main theatre.

In considering the defensive as a general plan of campaign the maxim is:  If not relatively strong enough to assume the offensive, assume the defensive till you become so—­

    (1) Either by inducing the enemy to weaken himself by attacks or
    otherwise;

    (2) Or by increasing your own strength, by developing new forces or
    securing allies.