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 superiority, to inflict any serious damage on the blockading
fleet on this line, and the only course left is to advance from the
Baltic against the north-eastern part of the blockading line. Here we
should have a tolerably secure retreat. This accentuates once more the
supreme importance to us of keeping open, at all costs, the passage
through the Sound and the Great Belt. The command of these straits will