 Seventeen ships were ordered in July 1915 as part of the 6th War Programme (as well as four of the Yarrow R class and three of the Thornycroft R class).Eight ships were ordered in December 1915 as part of the 7th War Programme (as well as two more of the Thornycroft R class).Twenty-three ships ordered in March 1916 as part of the 8th War Programme (as well as three more of the Yarrow R class), of which twelve were to the same design as the previous batch.