Coastal Motor Boat

• Losses [4]
• 1917 Zeebrugge action

In December 1916, the 3rd CMB Division proceeded to Dunkirk under the command of Lieutenant W.N.T. Beckett of CMB4 and operated on the Belgian coast. On 7 April 1917, the 3rd CMB Division attacked a group of German destroyers anchored at Zeebrugge. As a result, one destroyer was sunk and one very seriously damaged. For these actions Beckett was mentioned in Despatches and was awarded the Distinguished Service Cross (DSC).[5]

• 1919 Baltic actions against the Soviet Red forces.

In June 1919 a force of two CMBs attacked Kronstadt and sank the cruiser Oleg. Lt. Augustus Agar of CMB4 won his Victoria Cross in this operation.[3]

In August, a larger combined operation with aircraft managed to damage one battleship and sink a depot ship. There were casualties as the mission came under heavy fire.[6] Lt. Agar won a DSO to accompany his VC.[7]

• 1919-1920 British Caspian Flotilla

In January 1919 a force of 12 CMBs was dispatched to the Caspian Sea (travelling by rail from Batumi on the Black Sea coast to Baku) to join a British naval unit supporting the anti-Bolshevik governments of Armenia, Azerbaijan and Georgia.[8]

The hull of CMB 4 in which Augustus Agar won his VC for the attack on Kronstadt naval base in 1919 and sank the cruiser Oleg was, for many years, at the Vosper Thornycroft works on Platt's Eyot on the Thames near Kingston. When these works closed it was restored and can now be seen in Boathouse 4 at Portsmouth Historic Dockyard where it is on loan from the Imperial War Museum, Duxford with details of these boats and the action. Agar’s VC is at the War Museum in London.

The hull of the other remaining example, CMB9, is identical to that of CMB4, for many years thought to be the sole survivor of the type. Her crew consisted of Archibald Dayrell Reed and Lieutenant Harold Drew. CMB 9 was converted to a Distance Control Boat in 1918, the first CMB so converted and in so doing became DCB1. The DCB role was and still is in part classified, completely autonomous, unmanned and radio controlled via aircraft, therefore can considered to be the first autonomous drone vessel. Following the success of the Royal Flying Corps drone ‘Aerial Target' aircraft trials in March 1917, A. M. Low's Experimental Works at Feltham adapted their radio control system, enabling two DCB craft to be controlled from one aircraft and proving in the 1918 trials that a flotilla of up to eight DCBs could be controlled in close formation.[9] At the conclusion of extensive post war trials CMB9/DCB1 was converted back to her original condition, remaining in service until 1950. She has been restored in her role as CMB9 and is based at Avonmouth and took part in the 2014 Remembrance Day events in Bristol. The boat is listed on the register of National Historic Ships, certificate no 2430.[10]

MTB 331, owned by Hampshire County Council and on-loan to the British Military Powerboat Trust (BMPT) at Marchwood, is the sole surviving 55' CMB.[13] Built in 1941, the penultimate 55' built, her design was based on that of the CMBs of 1917 with two V12 engines. Her post-war history is incomplete, but she was registered as the Jonrey at Teignmouth, then later at Bristol. She was acquired by the Council around 1990. Some restoration after this was carried out at Priddy's Hard, then she was transported by road to BMPT Marchwood in March 2000.[14]