"Implacable", the sole surviving member of the class, joined the Dardanelles operations in March 1915 and saw action during the landings at Cape Helles in April. She was later withdrawn, first in May 1915 to reinforce the Italian fleet guarding the Adriatic Sea and then to Salonika in November that year. After being recalled to Britain in July 1917, she was converted into a depot ship and used to support the Northern Patrol. After the war, she was sold for scrap in 1921 and was broken up in 1922.