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by Lt Cdr Geoffrey B Mason RN (Rtd) (c) 2001

HMS UNICORN - Aircraft Maintenance/Light Fleet Aircraft Carrier
including Convoy Escort Movements

HMS Unicorn (Navy Photos, click to enlarge)

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G e n e r a l   I n f o r m a t i o n


This ship was the first Royal Navy aircraft carrier to be purpose built for use as a Repair and Maintenance vessel for aircraft. However she was fitted with a full length flight deck to enable landings or launch of existing types of carrier borne aircraft and so could also be deployed for operational use as a Fleet carrier. Her hangars were intended to house any type of aircraft used by the RN including amphibians which could be embarked by crane and launched from a catapult. The lifts were large enough to accommodate the larger amphibians. This ship saw operational service as a Fleet Carrier during WW2 and could act as a landing platform if any accompanying Fleet Carrier was unable to land aircraft after action damage. Maintenance workshops with ample capacity for carrying stores required for aircraft maintenance and repair as well as for ship equipment were provided.


Her designed displacement was 16,510 tons at full load with an overall length of 640 feet, a Beam of 90 feet and draught of 19 feet at full load.  Turbine machinery of 40,000 SHP drove two shafts to provide a speed of 22 knots. Her main armament was four twin 4” AA mountings with 2pdr Pom Pom mountings all of which were radar controlled. These were supplemented by 20mm Close Range Oerlikon mountings during service. An aircraft warning radar Type 281B was fitted to provide aircraft control and give warning of air attack. Hangar space enabled about 35 aircraft to be fitted for operational use and housed aircraft embarked for repair or when ship was deployed as a Ferry Carrier. The number carried depended on the type of aircraft and was fewer after WW2 when these were larger. Her complement including aircrew if used operationally was over 1,000.


The value of this type of aircraft carrier was fully justified both during WW2 in the Mediterranean and later during UN service in Korea when she was used as a Ferry Carrier as well as in the maintenance role. A proposal made after she had been placed in Reserve for the second time was that she be converted for use as a troop carrier but this was not accepted and she was then sold for scrap.




UNICORN Class Aircraft Maintenance and Repair aircraft carrier ordered from Harland and Wolff at Belfast on 14th April 1939 and laid down on 29th June that year. Launch on 20th November 1941 was delayed by suspension of work on several occasions because of higher priority being given to completion of work on smaller warships required for convoy defence. She was the 14th RN ship to bear this name, introduced in 1544 for a 36 gun ship taken from the Scots at Leith. It had last been used for 1 5th Rate built at Chatham in 1824 and still afloat Dundee after WW2 renamed CRESSY. This latter ship was then eldest serving RN warship still in the water and remained in use as the headquarters of the Tay Division RNR until 14th July1959 when sold for demolition. Build of this maintenance carrier was completed on 12th March 1943.


B a t t l e   H o n o u r s


ARMADA 1588 - CADIZ 1596 - PORTO FARINA 1655 -  SANTA CRUZ 1657 - LOWESTOFT 1665 - ORFORDNESS 1666 - SOLEBAY 1672 - SCHOONEVELD 1673 - TEXEL 1673 - VESTALE Action 1761* - TRIBUNE Action 1796* - BASQUE ROADS 1809 - SALERNO 1943 - OKINAWA 1945 - KOREA 1950-53

(*  Single Ship Actions.)


H e r a l d i c   D a t a

Badge:  On a Field Blue, a unicorn rampant White, armed and winged Gold.



D e t a i l s   o f   W a r   S e r v i c e


(for more ship information, go to Naval History Homepage and type name in Site Search



1 9 4 3


March                    Contractors harbour trials

                                Commissioned for service with Home Fleet.

                12th        Build completion and commenced Acceptance Trials in Clyde area.

                                Embarked aircraft.


April                       On completion of trials, storing and weapon trials took passage to join Home Fleet

to May                   at Scapa Flow.

                                Deployed for landing trials, aircrew training and work-up for operational service with

                                ships of Home Fleet based at Scapa Flow.


June                        Home Fleet work-up in continuation.



                27th        Took part with HM Aircraft Carrier ILLUSTRIOUS in offensive Home Fleet sweep off

                                Norway to simulate threat of invasion in Norway and as a diversion during allied HUSKY

                                landings in Sicily (Operation GOVERNOR)

                                (Note:  Cover of flying operations was provided by HM Battleships ANSON and DUKE

                                OF YORK, cruisers of Home Fleet and screen of destroyers from Scapa Flow.)



                5th          Deployed with HMS ILLUSTRIOUS in NW Approaches to carry out anti-submarine air

                                patrols in support of surface operations for convoy defence by Western Approaches Escort

                                and Support Groups.

                                Nominated for service in Mediterranean with Force V for support of planned allied landings

                                at Salerno, Italy (Operation AVALANCHE)

                                Passage via Gibraltar to join ships of Force V


September             Joined HM Escort Aircraft Carriers ATTACKER, BATTLE, HUNTER and STALKER

                                in Mediterranean in Force V.

                                (Note:  Force V –Task Force 88 (Rear Admiral Vian)). Support Carrier Force also comprised

                                HM Cruisers EURYALUS, CHARYBDIS and SCYLLA, HM Destroyers


                                CALPE, HAYDON, Polish destroyers SLAZAK and KRAKOWIAK.)


October                  On release from detached service with Force V took passage to Scapa Flow to resume

                                Home Fleet duties.


November              Deployment with Home Fleet in continuation


December              Nominated for transfer to Eastern Fleet

                30th        Took passage to Trincomalee with HM Battleships QUEEN ELIZABETH, VALIANT,

                                HM Battlecruiser RENOWN and HM Aircraft Carrier ILLUSTRIOUS screened by Home

                                Fleet destroyers and Frigates.



1 9 4 4


January                  Passage in Mediterranean to Alexandria.

                12th        Frigates detached on arrival at Alexandria.


                30th        Arrived at Trincomalee via Red Sea to join Eastern Fleet.


February                Deployed with eastern Fleet during exercises to prepare for planned air operations

to                            against Japanese installations in Sumatra.

November              (Note:  During this period ship was deployed as a Fleet aircraft carrier since her flight

                                deck could be used for normal flying operations. The ship was also available for

                                transport of aircraft and had repair facilities if required. No record of participation

                                in operational attacks with Eastern Fleet can be traced.)

                                Nominated for transfer to British Pacific Fleet


December              Passage in Indian Ocean to Fremantle



1 9 4 5


January                  Nominated for special duty.

                14th        Deployed with HM Cruiser SUFFOLK, HM Destroyers ULSTER, QUIBERON (RAN)

                                and QUICKMATCH (RAN) as escort for commercial liner during passage from

                                Fremantle to Sydney with HRH Duke of Gloucester to take up

                                his appointment as Governor General.

                20th        Deployed at Sydney to prepare for service in British Pacific Fleet


February                Joined Fleet Train Task, Force 112 for aircraft repair and transport in support of air

                                operations by Fleet Aircraft Carriers of British Pacific Fleet.

                                Took passage to Manus, in Admiralty Islands with ships of Fleet Train to await transfer

                                British warships for service in 5th US Fleet in SW Pacific.

                                (Note:  Before formal transfer to US Navy overall command ships other than Fleet

                                Train were identified as Task Force 113.)

                16th        Arrived at Momote, Manus with Fleet Train

                                (Note:  For details of Fleet Train composition and function see THE FORGOTTEN

                                FLEET by J Winton.)

March                    Deployed at Manus

                15th        British Pacific Fleet transferred and became Task Force 57.

                                (Note:  Some ships required for replenishment went to the US Forward Base at

                                Leyte after the transfer. See above reference and WAR WITH JAPAN (HMSO)


April                       Deployed at Manus for aircraft repair and use as a Ferry Carrier in support of

                                aircraft carrier deployed for air attacks on Japanese islands in Sakishima

                                Gunto Group during US landings on Okinawa (Operation ICEBERG I)

                                Transferred to Leyte for aircraft repair duties when Task Force 57 returned from

                                ICEBERG I.


May                        Took passage to return to Manus after ships of Task Force 57 sailed to continue air

                                operations off Sakishima Gunto (Operation ICEBERG II)

                                Deployed at Manus for repair duties.


June                        Returned to Sydney to prepare for planned operations against Japanese mainland by

                                British Pacific Fleet, now designated Task Force 37 and attached to US 3rd Fleet.

                24th        Took passage to Manus to provide aircraft repair during planned operations off Japan.


July                         Aircraft repair and transport duties based at Manus in continuation.

                                (Note:  Replacement aircraft required were ferried from Sydney to Manus.)


August                  Manus duties in continuation.


P o s t   W a r   N o t e s


HMS UNICORN remained in the Far East after VJ Day and was deployed with the British Pacific Fleet, which had returned to RN control. Task Force 112 was disbanded after the termination of operations off the mainland of Japan. The ship carried out aircraft repair and support of Fleet Air Arm aircraft carriers and took part in the extensive activities to return military and civil. personnel held in captivity by Japan in the Far East. In December 1945 she was nominated for return to UK and arrived at Devonport on 16th January 1946. She was Paid-off and de-stored prior to reduction to Reserve status.


Brought forward for service in 1948 she was refitted for use as a Maintenance and Replenishment aircraft carrier. In 1949 after recommissioning she was deployed to support HM Light Fleet Aircraft Carrier TRIUMPH  which had been transferred to the Far East to reinforce the RN presence after deterioration of relations with communist China. Retained in the Far East after the outbreak of the Korean War she was used to ferry aircraft between the aircraft carried deployed off Korea as part of the UN naval operations off Korea and Singapore for repair. On release from Far East service in 1954 she returned to UK and was again Paid-off into Reserve. She refitted in 1955 to up-date her repair facilities but remained in Reserve on completion. Placed on the Disposal List in 1958 as part of the reduction of the number of ships in Reserve, she was placed on the Disposal List and sold to BISCO the next year. The ship arrived in tow at Dalmuir on the Clyde for demolition by Arnott Young on 15th June 1960 and was later towed to Troon to complete the work.





Convoy Escort Movements of HMS UNICORN

by Don Kindell






Date convoy sailed

Joined convoy as escort

Convoy No.

Left convoy

Date convoy arrived








WS 030





KMF 015





MKF 015








(Note on Convoys)



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revised 14/10/10
further editing and formatting is required