(c) Superior concentration so as to render impotent the enemy's force available in the special theatre of operations (masking or containing). BLOCKADE Blockades are of two natures, according to the object review. The object may be:-- (d) Blockade. i. _Close blockade_ to prevent the enemy putting to sea. The object being usually to secure local or temporary control. ii. _Observation blockade_, to force the enemy to put to sea _by occupying the common lines of communications_ (_see_ below). In this case you are seeking a decision as a step towards general control. Both natures are operations upon the lines of passage and communication, but in case (1) the primary intention is defensive, to secure our own line; in case (2) the primary intention is offensive, to seize the enemy's line and compel him to expose himself in an attempt to recover it. GENERAL RULES FOR CONDUCTING BLOCKADES In case (1) (defensive intention) blockade should be as close as is compatible with security from torpedo attack. In case (2) (offensive intention) it should be as distant as is compatible with bringing enemy to action if he comes out. Examples:--_Case_ (1): First stage of Togo's blockade of Port Arthur. _Case_ (2): Nelson off Toulon. _Confusion of the two_: Sampson's attempt to close Santiago simultaneously with an attempt to force Cervera to sea. THE PECULIARITY OF MARITIME COMMUNICATIONS Since the whole idea of command of the sea and the whole theory of blockade rest on the control of communications, neither can be fully apprehended without a thorough understanding of the nature of maritime communications. Ashore, the respective lines of communications of each belligerent tend to run more or less approximately in opposite directions, until they meet in the theatre of operations or the objective point. At sea the reverse is the case; for in maritime warfare the great lines of communications of either belligerent tend to run approximately parallel, if, indeed, they are not identical. Thus, in the case of a war with Germany, the object of which lay in the Eastern Mediterranean, or in America, or South Africa, our respective lines of communication would be identical. This was also the case in all our imperial wars with France. _This peculiarity is the controlling influence of maritime warfare._ Nearly all our current maxims of Naval strategy can be traced to the pressure it exerts on Naval thought. It is at the root of the fundamental difference between Military and Naval strategy, and affords the explanation of much strategical error and confusion, which has arisen from applying the principles of land warfare to the sea without allowing for the antagonistic conditions of the communications and operations against them in each case. On land the chief reason for not always striking the enemy's communications at once is that as a rule we cannot do so without exposing our own.