These boats had been captured by the Germans and impressed into this work.
There are also stories of Irish boats and Norwegian trawlers in this work, but I secured no confirmation of such reports.
It is still unsettled in British Admiralty circles as to whether the "Audacious" came in contact with a mine or torpedo from a German submarine.

Two of her crew report that they saw the wake of a torpedo.
Reports that the periscope of a submarine showed above the water I have reason to reject.
English reports were suppressed--the admiralty claimed this right, since there was no loss of life--in the belief that if the ship was torpedoed by a submarine, the Germans would give out the first report, and thereby be of assistance in determining the cause.

But to-day the Germans have their doubt as to where the "Audacious" is, and as to whether or not she was ever really sunk.
Expert opinion is divided in authoritative circles in England as to the cause of the disaster; but more than 400 mines have been swept up along the Irish and Scotch coasts by the English mine sweepers.
While upon this subject, I ought to narrate that the study of this topic has convinced me that the Germans have a long task if they hope within a reasonable number of months to reduce by submarine torpedo practice the efficiency of the English navy to a basis that will warrant German warships coming forth to battle.
Every battleship is protected by four destroyers.

Submarines, when detected, are the most easily destroyed craft.

They have no protection against even a well-directed rifle bullet.