11th MCM Squadron The 11th Mine Countermeasures Squadron was a unit of the British Royal Navy during the Falklands War of 1982 . Unit history . Background . On 2 April 1982 , Argentina invaded the Falkland Islands . Intelligence from a submarine reported the laying of a defensive minefield off the approaches to Port Stanley ( the capital of the islands ) . Great Britain had supplied Argentina with modern influence mine s , both combination magnetic and pressure activated , and had recently actually serviced them for the Argentinian Navy . The Royal Navy ' s mine warfare capacity was purely coastal with s with a range of around , totally unsuitable for either the distance or the conditions . A plan existed from the Cold War years for the sweeping of Soviet minefields in the English Channel and North Sea , in the event of needing to reinforce Europe in time of war with Russia . It revolved around a number of deep sea trawlers ( approx ) being earmarked and kept in " readiness " for conversion . Five ships were called to Rosyth dockyard where in three days they were stripped of their fishing equipment , their holds were emptied of frozen fish , and Extremely Deep Armed Team Sweep ( EDATS ) equipment was fitted . They were hastily commissioned , and crews , mainly from the Rosyth - based 1st MCM Squadron were assembled , bolstered by technical specialists from elsewhere . The group was designated the 11th MCM Squadron under the command of Lieutenant - Commander Martyn Holloway , the captain of . The plan was based on the assumption that the Argentinians would have surrendered by the time they got there , and the sweepers would simply clear the minefields . They were unarmed except for two light machine gun s on the bridge wings , with a single engine , single screw configuration , only two or three watertight compartments , and were inherently difficult to handle . Training and preparation . After a two - day work - up , basic drills on operating unfamiliar equipment were carried out with instruction from the merchant service crews , who then disembarked . Four of the ships sailed on 25 April and followed the next day , to catch them up " en route " . Drills were practised with the mainly unfamiliar EDATS in the waters off North Africa . As the weather warmed , the daily task of locating discarded fish around the ships became more important , the stench often leading to fish that had slid under equipment before decaying . On 11 May , the squadron anchored off Ascension Island , and refuelled , although the ships had the capacity to travel the to the operational area and return to the UK on one tank . The ships were then ordered to sail for South Georgia on the 13th , arriving on 25 May . They were used there as utility vessels , transporting stores and men , particularly Gurkhas , Scots and Welsh Guards between the ships they had made the journey down on , to the generally smaller craft which would take them to the landing , often in appalling conditions of force 10 katabatic winds and driving snow . They were then ordered on 5 June to sail to the edge of the Total Exclusion Zone ( TEZ ) which was in theory outside the range of land - based aircraft . After the landings , the squadron sailed into and anchored in " bomb alley " in San Carlos Water on 9 June . The war zone . The Argentines had not surrendered , so these ships were then used at night to transport Special Forces , such as SAS and Royal Marines , mainly into West Falkland , where they were inserted covertly by Gemini RHIB . They had to be back inside the Rapier ( air defence missile system ) protection of San Carlos or Teal Inlet by dawn as they were defenceless to air attack in the open sea . This was a hazardous undertaking , operating in confined and shallow waters with photocopies of hand drawn charts from the 1920s in many cases . On one occasion , HMS " Pict " was dropping troops at Saunders Island with an onshore force 7 and struck a reef just as the Geminis were slipped down the rear trawlnet chute . Luckily the ship came off with no more than a large dent in the bottom . On the night of 11 June , HMS " Pict " was ordered to sweep the entry to Berkeley Sound and mark a cleared channel for a frigate to enter and shell with fire support ( NGFS ) , the Argentinian mountain positions guarding Port Stanley for the final infantry assault . The five ships were utilised massively as general workhorses , often in circumstances where their potential loss was viewed as a good alternative to a major fleet unit . The Argentinian forces surrendered on 14 June , and the ships were ordered to proceed as soon as possible to Port Stanley and clear the immediate approach to the harbour . After entering port , there followed several days of uncertainty as to whether or not the Argentinian mainland would carry on the fight . Minesweeping , especially in EDATS , leaves a minesweeper extremely vulnerable to air attack . Whilst in harbour , the MCD specialists in the squadron had set up a trisponder network , which allows navigational accuracy to in the Port Stanley approaches . Two Argentinian officers in a very gentlemanly gesture , presented a chart showing the locations that 21 mines were laid , in two fields with a defined channel between them . The more sophisticated influence mines had apparently been utilised in a defensive pattern off Buenos Aires , in case of a British attack on the mainland , and very simple contact moored mines were laid in the Falklands . It was eventually judged safe on 22 June to commence the clearance operations . Initially using the safer but less sure Oropesa system , the squadron swept 11 of the mines . Bad weather — up to force 12 on occasions — seemed to have moved the rest out of position . The very accurate EDATS system was then used to ensure full clearance . The operation was completed on 5 July . On the 13th , the squadron was released for a return to the UK via Gibraltar , a total distance of , arriving in mid - August , when the individual ships were returned to their owners .