HM Coastal Motor Boat 4

{{Short description|First World War torpedo boat}}

{{Use dmy dates|date=November 2017}}

{{Use British English|date=November 2017}}

{{Infobox ship begin}} {{Infobox ship image |Ship image=File:HM CMB No4 (1920).jpg |Ship caption=HM CMB No 4 in Imperial War Museum London (1920) }} {{Infobox ship career |Hide header= |Ship country=United Kingdom |Ship flag={{shipboxflag|United Kingdom|naval}} |Ship name=HM Coastal Motor Boat 4 |Ship namesake= |Ship ordered=1916 |Ship builder=John I. Thornycroft & Company |Ship laid down= |Ship launched= |Ship acquired=1916 |Ship commissioned= |Ship decommissioned= |Ship in service= |Ship out of service=1919 |Ship struck= |Ship honors= |Ship fate= |Ship status=Museum ship |Ship notes= }} {{Infobox ship characteristics |Hide header= |Header caption= |Ship type=Coastal Motor Boat |Ship displacement=5 tons |Ship length={{convert|45|ft|abbr=on}} |Ship beam={{convert|8|ft|6|in|abbr=on}} |Ship draft={{convert|2|ft|9|in|abbr=on}} |Ship propulsion=1 shaft Thornycroft V-12 petrol engine which developed {{convert|275|bhp|abbr=on}} |Ship speed={{convert|24.8|kn|km/h mph|abbr=on}} |Ship complement=3 |Ship armament=1 × 18-inch torpedo |Ship notes= }}

HM Coastal Motor Boat 4 is the torpedo boat used when Lieutenant Augustus Agar earned a Victoria Cross for carrying out a raid on Soviet warships in Kronstadt and sinking the cruiser Oleg.

It was one of a large series of small, fast, shallow draught Coastal Motor Boats used during the First World War. She was designed by John I. Thornycroft & Company of Hampton, England, ordered in January 1916, built by them and delivered that summer.

CMB 4 was {{convert|45|ft|m|0}} long and {{convert|8|ft|6|in|m|abbr=on}} in the beam. She displaced 5 tons drawing {{convert|2|ft|9|in|m|abbr=on}} of water. Power was a {{convert|275|bhp|abbr=on}} Thornycroft V-12 petrol engine driving a single propeller and achieved a top speed of {{convert|24.8|kn|km/h}}. The boat was armed with one 18 inch (450 mm) torpedo and two single .303 in (7.62 mm) Lewis machine guns for the attack on Oleg. It was operated by a crew of three.

File:IWM Duxford 2017 CMB4.jpg in October 2017.]]

In May 1916, Lieutenant W. N. T. Beckett took command of the newly built HM Coastal Motor Boat 4. In December 1916 he proceeded to Dunkirk in charge of the 3rd CMB Division and operated on the Belgian coast. Beckett was in command of a Divisional CMB attack on German destroyers at Zeebrugge on 7 April 1917; as a result one was sunk and one very seriously damaged. For these actions Beckett was mentioned in Despatches and was awarded the Distinguished Service Cross (DSC).{{cite web

|url=http://www.unithistories.com/officers/RN_officersB.html#Beckett_WNT

|title=Royal Navy (RN) Officers 1939-1945 - B

}}

The boat, under the command of Lieutenant Augustus Agar, was made famous by his part in the British operations in the Baltic Sea against the Bolsheviks in 1919, where she operated with her sister ships in activities such as the raid on Kronstadt.{{cite web

|url = http://www.naval-history.net/WW1AreaBaltic1919.htm

|title = War in Russian Bolshevik Waters 1919

|year = 2009

|publisher = Naval-history.net

|access-date = 5 August 2011

}}

After the action the boat was returned to the United Kingdom, where it was on display first at the Imperial War Museum in London and then at the Vosper works on Platt's Eyot (island) on the River Thames near Kingston for many years with a Victoria Cross painted on the side until the Vosper works there closed. It was then restored and displayed (with details of the action but with the painted VC removed) at the Imperial War Museum's out-station Imperial War Museum Duxford near Cambridge.{{cite web |url=http://www.iwm.org.uk/collections/item/object/30004029 |title=ship, Coastal Motor Boat (CMB 4) - MAR 563 |author=Imperial War Museum |author-link=Imperial War Museum |date=2012 |work=Imperial War Museum Collections Search |access-date=16 February 2012}} In July 2019 the boat was moved to Boathouse 4 in the Portsmouth Historic Dockyard, where she is being displayed above a full-size, working replica being constructed by volunteers. The replica boat will be ready for sea trials in the spring of 2022. CMB 4 remains in the ownership of the Imperial War Museum, and is currently on loan to Boathouse 4 until 2024.

Agar's VC is held by the Imperial War Museum in London.{{cite web |url=http://www.iwm.org.uk/collections/item/object/30008577 |title=Victoria Cross & VC - OMD 2409|author=Imperial War Museum |date=2012 |work=Imperial War Museum Collections Search |access-date=16 February 2012}}

The boat was inscribed on the National Register of Historic Vessels in May 1996, becoming part of the National Historic Fleet.{{cite web

|url = http://www.nationalhistoricships.org.uk/ships_register.php?action=ship&id=400

|title = National Register of Historic Vessels: CMB 4

|year = 2011

|publisher = National Historic Ships

|access-date = 5 August 2011

|archive-date = 5 July 2011

|archive-url = https://web.archive.org/web/20110705070624/http://www.nationalhistoricships.org.uk/ships_register.php?action=ship&id=400

|url-status = dead

}}