 After June 1917 , U @-@ 70 only sank another three ships throughout the rest of the war , one of which was the British Flower @-@ class sloop Rhododendron on 5 May 1918 . Rhododendron had been constructed in 1917 as a purpose built Q @-@ ship , a warship disguised as a merchant ship to lure German submarines within range of their concealed gun batteries . The sloop was patrolling off Mull Head in the Orkney Islands when struck by a single torpedo from U @-@ 70 . The captain , Lieutenant Commander Charles Arthur Peal , became disoriented in the aftermath of the explosion , and instead of ordering away a " panic party " to draw the submarine within range , ordered the complete evacuation of the ship , which was carried out in great haste and confusion . U @-@ 70 approached the burning ship and observed the chaotic evacuation , seizing a petty officer from a liferaft who revealed the ship 's true identity . U @-@ 70 shelled the wreck and escaped without coming under fire . Rhododendron capsized and sank the following morning , with the loss of 15 men , four killed in the explosion and 11 drowned during the evacuation . Peal and the rest of the crew were heavily criticized for their conduct under fire by an Admiralty board . 
