Owing to the late arrival of most of the class, they were unable to have much impact in service, only destroying two German submarines U-51 and UB-52 for the loss of four of their own number.

At the outbreak of the Second World War, the class was obsolete, but retained in training and coastal warfare roles to help the Royal Navy cope with heavy losses to the submarine fleet during the early stages of the war.

When the U.S. government discovered the construction, they impounded all the completed units, releasing them only following their own declaration of war two years later.

To escape this difficulty, the British government gave six units to the Chilean Navy as partial payment for the appropriation of six Chilean ships for British service in 1914: Group 3 was the largest group, and was constructed in 1917–1919 in Britain, shipyard space having been granted to the project and more boats needed following the seizure of those building in the United States.

They were built by Vickers, Cammell Laird, Armstrong Whitworth and William Beardmore at several locations, and most of the boats enjoyed long careers in the Royal Navy: