Their whole protection is that of invisibility.

Their plan of operation is to reach a position during the night, whence in the early morning they can single out an unprotected warship or cruiser not in motion, and launch against her side a well-directed torpedo, before being discovered.
The place for England's battleships is where they are: in the harbors with their protecting nets down until they are called for in battle.
In motion or action, submarines have little show against them.
The Japanese at Port Arthur found that protecting nets picked up many torpedoes and submarines.

Since that time, torpedoes have been made with cutting heads to pierce steel nets encircling the warships, but their effectiveness has not so far been practically demonstrated.
It is Kitchener's idea to keep the enemy guessing.

Therefore he was rather pleased than otherwise when the story of Russians coming through England from Archangel was told all over the world.

The War Office winked at the story and certainly had no objection to the Germans getting a good dose of it.