Such close blockade offers various possibilities of damaging the enemy, if the coast fortifications are so constructed with a view to the offensive that the fleet may rally under their protection, and thus gain an opportunity of advancing from their stations for offensive operations.  Such possibilities exist on our north coast, and our efforts must be turned towards making the most varied use of them.  We must endeavour by renewed and unexpected attacks, especially by night, partly with submarines and torpedo-boats, partly with battleships, to give the blockading fleet no breathing-time, and to cause it as much loss as possible.  We must not engage in a battle with superior hostile forces, for it is hardly possible at sea to discontinue a fight, because there is no place whither the loser can withdraw from the effect of the enemy’s guns.  An engagement, once begun must be fought out to the end.  And appreciable damage can be inflicted on the enemy only if a bold attack on him is made.  It is only possible under exceptionally favourable circumstances—­such, for example, as the proximity of the fortified base—­to abandon a fight once begun without very heavy losses.  It might certainly be practicable, by successful reconnoitring, to attack the enemy repeatedly at times when he is weakened in one place or another.  Blockade demands naturally a certain division of forces, and the battle-fleet of the attacking party, which is supposed to lie behind the farthest lines of blockade and observation, cannot always hold the high seas in full strength.  The forces of the defending party, however, lie in safe anchorages, ready to sally out and fight.

Such a blockade might, after all, be very costly to the attacking party.  We may therefore fairly assume that the English would decide in favour of the second kind.  At all events, the harbour constructions, partly building, partly projected, at Rosyth and Scapa Flow, were chosen with an eye to this line of blockade.  It would entail in the north the barring of a line about 300 nautical miles long, a scheme quite feasible from the military aspect.  Only a small force is required to seal up the Channel, as the navigation route is very narrow.  In addition to all this, the great English naval depots—­Dover, Portsmouth, Portland, and Plymouth—­are situated either on the line of blockade or immediately behind it.  Besides, every advance against this line from the north is flanked by Sheerness and Harwich, so that a retreat to the German coast might be barred.  The conditions for the northern line of blockade will be no less favourable when the projected harbour works are finished.  The blockading fleet finds, therefore, a base in the great harbour of Rosyth, while a cruiser squadron might lie in support off the Orkney Isles.  Every attacking fleet from the German north coast will be unhesitatingly attacked on the flank from Rosyth and Sheerness, and cut off from its line of retreat.  It is thus almost impossible, owing to the English