Page "Baralong Incidents" Paragraph 2

After the sinking of the RMS Lusitania by a German submarine in May 1915, Lieutenant-Commander Godfrey Herbert, commanding officer of Baralong, was visited by two officers of the Admiralty's Secret Service branch at the naval base at Queenstown, Ireland.

He was told, " This Lusitania business is shocking.

Unofficially, we are telling you ... take no prisoners from U-boats.