|42 Commando Royal Marines|
|Active||1943 – present|
|Part of||Naval Service|
|Garrison/HQ||Bickleigh Barracks, Devon|
|Motto(s)||Per Mare Per Terram|
(By Sea By Land) (Latin)
|Lt Col Doug Pennefather RM|
|Captain-General||The Duke of Sussex (Captain-General, Royal Marines)|
42 Commando (pronounced as Four-Two Commando) is a subordinate unit within the Royal Marines 3 Commando Brigade, the principal Commando formation, under the Operational Command of Fleet Commander.
Tasked as a Commando unit, 42 Cdo RM is capable of a wide range of operational tasks. Based at Bickleigh Barracks near Plymouth, personnel regularly deploy outside the United Kingdom on operations or training. 42 Commando is a specialised unit for maritime operations, meaning some of the posts within the unit, like heavy weapons specialists, could be reallocated across the Royal Navy.
All personnel will have completed the Commando course at the Commando Training Centre (CTCRM) at Lympstone in Devon, entitling them to wear the green beret, with attached personnel having completed the All Arms Commando Course.
Early Commando units were all from the British Army but by February 1942, the Royal Marines were asked to organise Commando units of their own, and 6,000 men volunteered.
No. 42 (Royal Marine) Commando was raised in August 1943, under the command of Lieutenant Colonel R C de M. Leathes from the 1st Royal Marine Battalion, as part of the expansion of the commandos. They were assigned to the 3rd Special Service Brigade and served in India and Burma in 1943–45, including operations in the Arakan and Assam. It took part in the third Arakan campaign and carried out a series of amphibious landings down the Burmese coastline. Including the landings at Myebon and the Battle of Hill 170. It then returned to India to prepare for Operation Zipper the invasion of British Malaya. The war ended before the operation began and the commando was diverted to reoccupy Hong Kong.
Following the Second World War 1st, 2nd and 4th commando brigades disbanded leaving only one brigade – the 3rd (40(RM), 42(RM) and 45(RM)). The Commando was involved in operations during the confrontation with Indonesia (Borneo). It was during this tour that the famous Limbang raid was conducted by Lima Company. Throughout the following decade it was based in Singapore at HMS Simbang (RNAS Sembawang).
After the return to the UK, the Commando was deployed to Northern Ireland, the New Hebrides in 1980 and exercised regularly overseas. More recently the Commando has seen operational service in South Georgia, Montserrat in 1995, Iraq and Afghanistan. 
In 1982, following the Argentine invasion of the Falkland Islands, the Commando deployed on Operation Corporate. On 21 May the Commando were Brigade reserve at San Carlos under Lt. Col. Nick Vaux RM. The unit was deployed to seize Mount Kent in a night move by helicopter. By 4 June the unit had moved forward, mostly under cover of darkness, to positions west of high ground overlooking Port Stanley and the last Argentine stronghold. After days of probing reconnaissance, a Brigade assault took place on the night of 11/12 June in which the Commando's task was to secure Mount Harriet on the Brigade right flank. By moonlight and in freezing temperatures, 42 Commando moved undetected through enemy minefields in a 9 km (5.6 mi) right-flanking movement to surprise the enemy in their rear. Consecutive assaults by "K" and "L" Companies followed, up steep slopes onto company positions. Against strong resistance and continuous artillery bombardment, the Marines prevailed. By first light more than 30 enemy had been killed and over 300 prisoners taken as 42 Commando consolidated on Mount Harriet. 42 Commando suffered two fatalities themselves – one on Mount Harriet and one on Wall Mountain.
For the bravery shown in the attack on Mount Harriet, 42 Commando was awarded one DSO, one Military Cross, four Military Medals and eight men were Mentioned in Dispatches.
The new millennium saw the Commando deploy on Operation Telic 1 for the invasion of Iraq in 2003 where they launched a helicopter assault on the Al-Faw Peninsula to support 40 Commando.
The unit returned from Operation Herrick in Afghanistan on 16 April 2009, where it served as the Regional Battle Group (South).
In May 2013, 42 Commando took over from 45 Commando as the lead Commando task group and deployed as part of the COUGAR 13 Response Force Task Group exercising in Albania and the Middle East.
In early July 2019, men from 42 Commando deployed by air to Gibraltar, in order to support the Gibraltar Government's detention of the Panama-flagged crude oil tanker Grace 1. The vessel was suspected of carrying oil to a Syrian refinery, in contravention of European Union sanctions against Syria.
In March 2020, personnel of the unit worked with the Peacekeeping Company of the Belarusian 103rd Guards Airborne Brigade at the Losvido Training Areas during the two-week Exercise Winter Partisan, which was the first time Armed Forces of Belarus have provided training to any nation.
42 Commando's current role is as the Royal Marines' Maritime Operations Commando (MOC) responsible for delivering two capabilities:
Prior to April 2017, the structure of 42 Commando followed the Commando 21 model. The current organisation of 42 Commando, in its MOC role, comprises four companies, each 120 strong, supported by Command and Logistics companies. The four companies are:
The following battle honours were awarded to the British Commandos during the Second World War.
Commanders have included: