Sherman DD Regiment

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  1. Trux

    Trux 21 AG

    ARMOURED REGIMENT DD TANKS


    Amphibious DD tanks were operated by normal armoured regiments with very little
    alteration to the organisation.


    AN ARMOURED REGIMENT – DD TANKS

    The DD regiment does not seem to have a War Establishment since it was a normal armoured regiment issued with Sherman DD amphibious tanks when required for specific operations.

    DD tanks were first used in action on D Day when they were issued to ordinary armoured regiments with only some of its tanks replaced by Sherman DDs. Two squadrons were amphibious while the third squadron landed later from landing craft. Regimental headquarters tanks were not amphibious. The regiments did receive Sherman Firefly tanks but these were not amphibious and were landed from landing craft. The assault regiments operated as normal armoured units once ashore, and as soon as was convenient they handed in the DD tanks in exchange for ordinary Sherman tanks. DD crews were trained in the use of the vehicles by 79 Armoured Division.

    Each DD regiment received forty DD tanks which were issued twenty per squadron. This allowed four for squadron headquarters plus four troops of four tanks each.

    DD tanks were next used for the operations concerned with clearing the Scheldt Estuary. A small number of DD tanks were used by one squadron which had just completed its training on this type. This small operation showed up many problems which were eventually solved by 79 Armoured Division.

    Over the winter of 1944/45 there was no need for amphibious tanks but two regiments were trained in their use. They were in action for the Rhine Crossing in 1945. For this operation entire regiments received DD tanks, and the reconnaissance troop used Buffalos to find or create exit points for the DD tanks.

    No changes appear to have been made to the personnel establishment but some re training was necessary.


    SHERMAN DD REGIMENT. D DAY.
    This is based on the available information. This includes the War Establishment table in force at the time plus changes that were known to have been made. Unit histories give much useful information.

    Total personnel
    Lieutenant Colonel
    Major, second in command
    4 X Major
    Captain, adjutant
    Captain, Technical Officer
    Captain Liaison Officer
    8 X Captain
    20 X Subaltern
    Quartermaster

    Regimental Serjeant Major
    Regimental Quartermaster Serjeant
    Quartermaster Serjeant, technical
    Mechanist Quartermaster Serjeant
    Squadron Serjeant Major

    4 X squadron quartermaster serjeant
    4 X serjeant mechanist
    orderly room serjeant clerk
    provost serjeant
    signal serjeant
    transport serjeant
    serjeant technical storeman
    29 X serjeant

    59 X corporal
    523 X trooper

    Total 670

    Plus
    Medical Officer RAMC
    3 X armourer REME
    4 X officers mess cooks ACC
    15 X cook ACC
    6 X vehicle mechanic REME


    Trades included
    carpenter and joiner
    13 X clerk
    94 X driver mechanics
    103 X driver operator
    5 X electrician
    equipment repairer
    gun fitter
    92 X gunner mechanics
    89 X gunner operator
    6 X storeman (technical)
    39 X vehicle mechanics

    22 X batman
    butchery dutyman
    90 X driver IC
    medical orderly
    6 X motorcycle orderly
    postman
    5 X sanitary dutyman
    5 X storeman
    4 X water dutyman

    Total vehicles
    8 X motorcycle
    1 X Car 4seater 4 X 4
    11 X car 5cwt 4 X 4 jeep
    12 X 15cwt GS
    1 X 15cwt Office
    4 X 15cwt water
    1 X 15cwt FFW
    7 X 15cwt halftrack
    48 X 3ton 4 X 4 GS
    3 X 3ton 4 X 4 stores
    1 X 3ton 4 X 4 kitchen
    4 X Carrier, Starting and Charging
    9 X scout car
    6 X AA tank
    61 X tank
    11 X light tank
    3 X armoured recovery vehicles
    1 X 180 gallon water trailer


    ORGANISATION
    Regimental Headquarters.
    This was the tactical headquarters of the regiment in action. The four tanks were control tanks which had extra wireless sets and less ammunition but were otherwise as for the other tanks in the regiment. Each tank had two Wireless set No19. All four tanks were linked on the same net using the one of the No19 sets but all had different links on the second set.


    Car 4 seater 4 X 4
    corporal driver IC, driver IC

    Cruiser Tank (Sherman 75mm) 1
    Lieutenant Colonel, Adjutant, serjeant, driver mechanic, driver operator.
    Cruiser Tank (Sherman 75mm) 2
    Major, Regimental Serjeant Major, operator RS, corporal driver mechanic, driver operator
    Cruiser Tank (Sherman 75mm) 3
    Subaltern, serjeant, driver mechanic, gunner operator, driver operator
    Cruiser Tank (Sherman 75mm) 4
    Intelligence Officer, intelligence corporal, gunner operator, driver mechanic, driver operator

    The above vehicles would land as soon as possible from Tank Landing Craft. They would be ashore by midday and ready to take command of the squadrons.


    Headquarters Squadron.
    This provided administrative and supply services for the regiment. None of the Headquarters Squadron vehicles were amphibious although the armoured vehicles were equipped for wading and all vehicles were waterproofed.

    In action the administrative vehicles were divided into echelons. F echelon contained those vehicles likely to be needed in the front line. These would include the medical vehicles, recovery and maintenance vehicles plus some 3ton lorries for ammunition and petrol. These vehicles landed from landing craft as soon as possible on D Day. Non essential vehicles landed over a period of days as circumstances and shipping allowed.

    Squadron headquarters.
    Car 15cwt 4 X 4 (jeep)
    Major (squadron commander), driver IC
    15cwt FFW
    Captain (squadron second in command), Squadron Serjeant Major,
    driver operator
    Carries a Wireless set No19.

    AA troop
    The AA troop was disbanded after the Normandy fighting since air superiority meant there was little employment for them. The crews were used as replacements. Some units found that the twin 20mm cannon were very useful when used against ground targets.

    AA Tank 1
    Subaltern, driver mechanic, gunner operator, driver operator
    AA Tank 2
    serjeant, driver mechanic, gunner operator, driver operator
    AA Tank 3
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    AA Tank 4
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    AA Tank 5
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    AA Tank 5
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    AA tank 6
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic


    Reconnaissance troop
    Troop headquarters
    Light tank 1
    Subaltern, driver mechanic, gunner operator, driver operator
    Light tank 2
    serjeant, driver mechanic, gunner operator, driver operator

    Section 1
    Light tank 3
    serjeant, driver mechanic, gunner operator, gunner mechanic
    Light tank 4
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    Light tank 5
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    Section 2
    Light tank 3
    serjeant, driver mechanic, gunner operator, gunner mechanic
    Light tank 4
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    Light tank 5
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    Section 3
    Light tank 3
    serjeant, driver mechanic, gunner operator, gunner mechanic
    Light tank 4
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic
    Light tank 5
    corporal driver operator, gunner mechanic, gunner operator, driver mechanic


    Intercommunication troop
    Scout Car 1
    serjeant, driver operator
    Scout Car 2
    driver operator, corporal driver IC
    Scout Car 3
    driver operator, corporal driver IC
    Scout Car 4
    driver operator, driver IC
    Scout Car 5
    driver operator, driver IC
    Scout Car 6
    driver operator, driver IC
    Scout Car 7
    driver operator, driver IC
    Scout Car 8
    driver operator, driver IC
    Scout Car 9
    Technical Officer, driver operator,

    Administrative troop
    Motorcycle 1
    provost serjeant
    Motorcycle 2
    motorcyclist
    Motorcycle 3
    motorcyclist
    Motorcycle 4
    motorcyclist
    Motorcycle 5
    motorcyclist
    Motorcycle 6
    motorcyclist
    Motorcycle 7
    motorcyclist
    Motorcycle 8
    batman

    Car 5cwt 4 X 4 (jeep) 1
    corporal driver IC
    Car 5cwt 4 X 4 (jeep) 2
    driver IC
    Car 5cwt 4 X 4 (jeep) 3
    driver IC
    Car 5cwt 4 X 4 (jeep) 4
    driver IC
    Car 5cwt 4 X 4 (Jeep) 5
    driver IC
    Car 5cwt 4 X 4 (jeep) 6
    Quartermaster, driver IC

    15cwt truck GS 1
    squadron quartermaster serjeant, driver IC
    15cwt truck GS 2
    sanitary dutyman, medical officers orderly, driver IC
    15cwt truck GS 3
    Quartermaster Serjeant (technical), serjeant (technical), storeman,
    corporal clerk, driver IC
    15cwt truck water
    water dutyman, driver IC

    15cwt halftrack
    Medical Officer, batman, driver IC
    15cwt halftrack
    driver IC
    For use as ambulance
    15cwt halftrack
    driver IC
    For use as ambulance

    15cwt halftrack
    mechanist serjeant, 3 X vehicle mechanic, driver operator
    Carries fitters and tools
    15cwt halftrack
    equipment repairer, serjeant armourer, 2 X armourer, corporal storeman (technical), driver IC

    3ton 4 X 4 GS 1
    transport serjeant, cook ACC (officers mess), butchery dutyman, batman, driver IC
    3ton 4 X 4 GS 2
    carpenter and joiner, vehicle mechanic, corporal driver operator, 3 X driver mechanics (relief), 3 X gunner operator (relief), 3 X gunner mechanic (relief), driver IC
    3ton 4 X 4 GS 3
    postman, storeman, 3 X batman, driver IC
    3ton 4 X 4 GS 4
    electrician, gun fitter, driver IC
    3ton 4 X 4 GS 5
    serjeant, sanitary dutyman, driver IC
    3ton 4 X 4 GS 6
    clerk, driver IC
    3ton 4 X 4 GS 7
    clerk, driver IC
    3ton 4 X 4 GS 8
    Regimental Quartermaster Serjeant, driver IC
    3ton 4 X 4 GS 9
    3 X vehicle mechanic, driver IC
    3ton 4 X 4 GS 10
    storeman, clerk, driver IC
    3ton 4 X 4 GS 11
    2 X clerk, driver IC
    3ton 4 X 4 GS 12
    Signal Officer, signal serjeant, serjeant clerk, corporal clerk, driver IC
    Used as regimental office.
    3ton 4 X 4 Kitchen
    serjeant cook, 2 X cook, driver IC

    Carrier, Staring and Charging
    electrician, driver mechanic
    Battery charging and maintenance
    3ton 4 X 4 store
    vehicle mechanic, technical storeman, 3 X batman, driver IC

    The Squadrons.
    Two squadrons were equipped with DD tanks as follows.
    Squadron headquarters
    This contained the vehicles and personnel essential to the command and control of the squadron in action. All four headquarters tanks were DD tanks and were connected on one wireless net via the Wireless set No19 B set while they all had a different net via the Wireless set No19 A set. These connected with regimental headquarters, B echelon and the troops

    Cruiser Tank 1 (Sherman DD)
    Major (squadron commander), serjeant, driver operator, gunner operator, driver operator
    Cruiser Tank 2 (Sherman DD)
    Captain, corporal driver operator, gunner operator, gunner mechanic,
    driver mechanic
    Cruiser Tank 3 (Sherman DD)
    Captain, driver mechanic, gunner operator, gunner mechanic, driver operator
    Cruiser Tank 4 (Sherman DD)
    Squadron Serjeant Major, driver mechanic, gunner operator, gunner mechanic, driver operator

    The following were not amphibious and were landed as soon as possible from landing craft.
    Car 5cwt 4 X 4 (jeep)
    driver IC

    Armoured Recovery Vehicle MkI
    Serjeant vehicle mechanic REME, vehicle mechanic, driver mechanic

    Administrative troop
    None of these vehicles was amphibious and would be landed as soon as possible according to their priority. Ammunition, petrol and food would have priority over blankets and stores.
    15cwt truck GS
    squadron quartermaster serjeant, serjeant, driver IC
    15cwt water
    water dutyman, driver IC
    15cwt halftrack
    mechanist serjeant, 2 X vehicle mechanic, driver operator (relief)
    15cwt halftrack
    cook (offices mess), driver IC
    15cwt halftrack
    2 X driver mechanic (relief), driver operator (relief), 2 X gunner operator (relief)

    3ton 4 X 4 GS 1
    storeman, 5 X vehicle mechanic, driver IC
    3ton 4 X 4 GS 2
    batman, driver IC
    3ton 4 X 4 GS 3
    batman, driver IC
    3ton 4 X 4 GS 4
    batman, driver IC
    3ton 4 X 4 GS 5
    clerk, corporal driver IC,
    3ton 4 X 4 GS 6
    clerk, driver IC
    3ton 4 X 4 GS 7
    batman, driver IC
    3ton 4 X 4 GS 8
    gunner operator (relief), driver IC
    3ton 4 X 4 GS 9
    gunner mechanic (relief), sanitary dutyman
    3ton 4 X 4 GS10
    2 X gunner mechanic (relief), driver IC
    3ton 4 X 4 GS 11
    corporal driver operator (relief), driver IC
    3ton 4 X 4 GS 12
    driver IC

    3ton 4 X 4 Kitchen
    corporal cook, 3 X cook, driver IC
    Carrier, Starting and Charging
    electrician, driver mechanic
    3ton 4 X 4 stores
    corporal storeman technical, 2 X vehicle mechanic, gun fitter


    The fighting troop.

    Troop 1
    Cruiser tank DD (Sherman 75mm)
    Subaltern, corporal driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    serjeant, driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic

    Troop 2
    Cruiser tank DD (Sherman 75mm)
    Subaltern, corporal driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    serjeant, driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic

    Troop 3
    Cruiser tank DD (Sherman 75mm)
    Subaltern, corporal driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    serjeant, driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic

    Troop 4
    Cruiser tank DD (Sherman 75mm)
    Subaltern, corporal driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    serjeant, driver operator, gunner operator, gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic
    Cruiser tank DD (Sherman 75mm)
    corporal driver operator, gunner operator, 2 X gunner mechanic, driver mechanic


    The organisation above is that for a normal regiment together with such changes as are known to have been made for this specific operation. Not all the vehicles were landed together. The D Day loading plans allowed for the follow up Reconnaissance troop, C Squadron and an F1 Echelon with essential supplies and equipment to be landed from landing craft on D Day. Other vehicles and personnel were landed when shipping was available.

    All the DD units taking part in the D Day landings were trained by 79 Armoured Division but did not operate under their control. Early in 1944 the DD regiments went to train with their assault divisions.

    The plan was that DD tanks would be launched 10,000 yards out to sea and then head towards the shore at 4 knots, led by Landing Craft Personnel. This would need careful timing since they were supposed to hit the beach with the first wave of infantry and clear the beaches before the other specialised armour arrived to engage pillboxes and strong points, and to breach or scale the sea walls. In the event bad weather conditions interfered with the plan.

    Only one regiment, 13/18 Hussars swam ashore, and they had to be launched from 5,000 yards to avoid the worst of the sea conditions. Forty DD tanks were embarked but six failed to launch. Of the remaining thirty four, three foundered and thirty one reached the beach. They did in fact arrive in time to help the infantry and then cover the other specialised armour as it landed. They then advanced inland with one squadron reaching the airborne forces at Pegasus Bridge.

    The other two British regiments landed and gave valuable support but their arrival was somewhat erratic and they were landed direct onto the beach from their landing craft at about the same time as the other specialised armour. These regiments were the 4/7 Dragoon Guards and the Sherwood Foresters Yeomanry.

    Despite the problems the contribution of the DD tanks should not be underestimated. Their arrival in the first stages of the assault was a surprise to the defenders and great help to the infantry in the first vital minutes. The arrival of those that swam ashore was a complete surprise since the defenders did not recognise the canvas boat shapes as tanks at all until they wallowed ashore, deflated their skirts and started firing.

    All tanks that were not DD were equipped with wading gear which consisted of trunking to allow air into the engine compartment and let exhaust out.

    All crew members wore escape apparatus in case the tank sank. However on D Day all the crew except the driver sat outside the tank. The commander needed to be outside in order to see and to steer.

    Landing Craft Personnel guides were older types of landing craft. They lacked a ramp but their bow shape made them good sea boats. They were manned by RN or Royal Marines.


    MARKINGS
    13/18 Hussars carried red numbers outlined in white.
    Numbers were assigned as follows
    Headquarters 10 to 20
    A Squadron 22 to 36
    B Squadron 44 to 58
    C Squadron 66 to 80
    Presumably the missing numbers were for headquarters vehicles.


    SHERMAN DD OPERATIONS on the SCHELDT.
    As part of the operation to clear the Scheldt estuary and open the port of Antwerp an amphibious assault was launched against South Beveland. This entailed crossing the estuary from south to north. The distance was some nine miles but part of it was on a sheltered tributary and the rest on the relatively sheltered estuary.

    A force of Buffaloes was assigned the assault and it was intended that they should be accompanied by DD tanks. At this time the Staffordshire Yeomanry were being converted to DD tanks from ordinary Shermans and only one squadron had finished training. This was to support the assault.

    The attack was launched in the early hours of 25 October 1944. Since it was still dark there was a need help with navigation. This was provided by navigation lights on the south bank and by Bofors guns firing tracer to indicate the correct direction.

    On arrival the DD tanks found their landing point too muddy and they had to look for an alternative. The dykes which ran all round the coast of the island to keep the sea out were all very steep and the tanks had trouble mounting them. When they succeeded they found that the ground was water logged and muddy to an extent that made manoeuvring difficult and this hindered the intended infantry support operations. Nevertheless the tanks gave valuable support.

    It was obvious from this operation that there were several problems to be solved before the next operation which was expected to be the Rhine Crossing, at a date which could not yet be predicted.

    79 Armoured Division set up Training and Experimental Wings to solve some of the problems. G wing was established in December to solve the problem of exiting a river after crossing it. Platypus grousers were of some help but the best answer was the carpet layer. Carpet laying devices on AVRE had been used on D Day and the idea was developed and adapted to the Buffalo. A set of rails was mounted on the Buffalo and a canvas carpet reinforced with palings was placed on top. As the Buffalo emerged from the water it lowered the end of the carpet which went under the tracks. This pulled the rest of the carpet down and rapidly laid a 75 foot length. Sherman DD tanks could mount the banks using this carpet to give grip. Of course it had a very short life but it only needed to survive a squadron using it.

    J Wing was established to study the problem of navigation. No single ideal solution was found but four methods were developed which when used in conjunction worked well. Radio direction keeping equipment was developed using two Wireless sets No 19 to give a beam which DD tanks, and Buffaloes could use as a guide. The traditional magnetic compass was used together with gyro compasses. Finally to enable crews to see where they were going the Tabby infra red lights and infra red beacons were used. All squadron commanders attended training courses in these devices and then trained their own personnel.




    ARMOURED REGIMENT. SHERMAN DD. CROSSING the RHINE.
    Regimental headquarters
    1 X car 4 seater 4 X 4
    3 X Sherman DD

    Headquarters Squadron
    Squadron Headquarters
    1 X Car 4 X 4 jeep
    1 X 15cwt FFW

    Reconnaissance troop
    This troop was to cross the river ahead of the main body and select good landing places for the DD tanks. Available accounts suggest that there was a headquarters section with LVT II and three sections, one per squadron. Each section seems to have had two LVT II with carpet laying equipment and one LVT IV carrying an airborne bulldozer to improve landing places.
    Probably
    2 X LVT II Command/Control
    6 X LVT II carpet layer
    3 X LVT IV with airborne bulldozers

    Intercommunication troop
    Although these Weasels seem to have been the amphibious M29C version they were carried across the river in LVT IV. They were particularly used on the river banks and flood plain where their low ground pressure gave them good mobility.
    9 X truck 10cwt tracked (M29 Weasel) or amphibian 10cwt tracked (M29C Weasel).

    Administrative troop
    8 X motorcycle
    6 X jeep
    3 X 15cwt GS
    1 X 15cwt water
    4 X 15cwt halftrack
    1 X 15cwt office
    10 X 3ton 4 X 4 GS
    1 X 3ton 4 X 4 kitchen
    2 X 3ton 4 X 4 stores
    2 X 3ton 4 X 4 DD compressor.
    1 X Carrier Starting and Charging

    3 X Squadron
    squadron headquarters
    1 X jeep
    3 X Sherman DD
    1 X ARV1
    3 X 15cwt GS
    1 X 15cwt water
    1 X 15cwt halftrack
    12 X DUKW
    1 X 3ton stores
    1 X Carrier S & C

    troop1
    4 X Sherman DD
    troop2
    4 X Sherman DD
    troop3
    4 X Sherman DD
    troop4
    4 X Sherman DD


    Royal Signals troop
    1 X jeep
    2 X 15cwt GS
    1 X 15cwt wireless house
    1 X 3ton 4 X 4

    Light Aid Detachment REME
    2 X motorcycle
    1 X jeep
    1 X 15cwt GS
    1 X 3ton 4 X 4
    1 X 3ton 6 X 4 Breakdown Gantry
    1 X 6 X 4 Heavy breakdown tractor

    The organisation above is that for a normal regiment together with such changes as are known to have been made for this specific operation. A considerable amount of time had been available for planning and training.

    Changes included
    - All Sherman tanks were DD amphibious tanks. None were Fireflies.
    - A Reconnaissance Troop of Buffaloes was included. These found suitable exit places and laid carpet to assist the tanks.
    - The Intercommunication Troop was equipped with Weasels
    - Two 3ton 4 X 4 DD compressor lorries were included at Regimental Headquarters. These were Fordson WOT6 which were used to refill gas cylinders for inflating the DD screens.
    - Amphibious DUKWs replaced 3 ton 4 X 4 in the squadrons.

    The Rhine Crossing began at 0200 hours on March 24 1945. There were two British DD units involved, The Staffordshire Yeomanry who had been training since October 1944, and 44 Royal Tank Regiment.

    For a river crossing the DD regiment needed a well planned and reconnoitred approach. Squadrons would need to approach close to the river bank with flotation screens lowered to avoid detection. They would then need an area where they could inflate the screen without attracting attention. A route to the river would be marked out and a site found where the tanks could enter the water at a suitable angle.

    There were also troops of LVT IV carrying flamethrowers. These were called Sea Serpent. Little is known about their organisation and distribution.


    SHERMAN DUPLEX DRIVE.

    In British service the DD tank was usually either a Sherman III (M4A2) with diesel engines or a Sherman V (M4A4) with a Multibank petrol engine. They different types were not usually found in the same unit.

    Bouyancy was provided by a rubberised canvas screen which was attached to a metal deck fitted round the hull just above the tracks. 36 tubular rubber pillars were fitted to the inside of the screen and when inflated they held the screen erect. The screen was held rigid by three metal hoops which surrounded the vehicle and by thirteen steel struts.

    The screen could be erected in about 15 minutes. In earlier versions the rubber pillars were inflated by compressed air from cylinders but later versions had a built in pump. The steel struts were then locked in place. On landing the screen could be deflated rapidly by opening air valves and the struts folded by hydraulic valves. The turret could then rotate and the main armament and co axial machine gun could be used. The hull machine gun could not be used until there was an opportunity to cut the canvas skirt away. For the Rhine Crossing the mechanisms were modified to allow the front of the screen to be collapsed so as to allow the armament to be used while the rear of the screen remained in place to prevent swamping as the tank climbed the river bank.

    The DD tank was powered by two propellers which were driven by the rear idler wheels, which in turn were powered by the tracks, which were powered by the normal transmission. The DD tank could be steered by the driver using the normal steering brake levers. These cut power to the tracks and thus to the propellers. However, the vehicle was best steered by the commander, standing on a platform on the outside rear of the turret. There was a support to hang on to and a tiller which pivoted the propellers to steer the tank. This position was somewhat exposed. Both the driver and commander had extended periscopes which allowed them to see over the screen so that the vehicle could be steered when closed down. On land the propellers could be tilted upwards so as to avoid obstacles.

    It was always a difficult decision for the crew whether to sit outside the tank in case it sank, or remain under the armour. The driver did not have a choice.
     
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