Landing Craft Assault

The Inter-Service Training and Development Centre takes a different view. It argues for the smallest possible unit, the eight-man infantry section, as the basis for initial assault craft.

Despite this, they acknowledge limitations. Any craft designed to withstand beach surf cannot, with economy, carry fewer than a platoon. This forms the basis for later designs such as the Landing Craft, Assault.

The committee also considers the craft required for the second wave of landings. They call for bigger, well protected landing craft. This line of thinking is advanced for its time. The Centre moves towards the later concept of the Landing Craft Infantry (Large), which can deploy up to two hundred soldiers in follow-up waves. Nevertheless, the committee decides to prioritise development of one type of craft, a personnel assault boat for platoon-level landings.

At the opposite end of the scale, upper limits on landing craft size are dictated by naval constraints. Ideally, the Inter-Service Training and Development Centre wants the Admiralty to build high-speed military transports. These would carry up to fourteen assault craft on davits and steam at forty-six kilometres per hour. Budget limitations make this impossible.

In practice, converted merchant vessels must serve the role. Most ocean-going passenger ships are already fitted with lifeboats capable of carrying ninety-nine people. In wartime, these lifeboats could be replaced with assault craft. This leads the Centre to conclude that the assault landing craft must weigh no more than ten tonnes. This restriction defines the limits of the Landing Craft, Assault design that follows.

In late 1938, the Inter-Service Training and Development Centre seeks help from the Admiralty to design a new landing craft, but the Admiralty declines. The Centre then turns to the Board of Trade, which refers them to Fleming of Liverpool, a firm known for lifeboat innovation. Fleming produces an initial design featuring a lightweight aluminium hull with a straight keel, a raised bow and stern, and a central troop compartment. The boat measures approximately 10.7 metres in length.

This design is tested at Portsmouth. Embarkation trials reveal practical issues, and tank testing raises concerns about low freeboard in rough seas. Fleming revises the design, adding higher sides, a bow ramp, and longitudinal seating. The updated craft is slightly longer and more seaworthy.

The Admiralty then requires competitive tenders. Only John I. Thornycroft & Co. Ltd. responds. Within two days, it submits a design based on similar principles but built in mahogany using conventional methods. The Thornycroft boat includes a bow ramp, recessed propellers, and a large superstructure with seating for troops and standing room beneath cover. It measures around 11.9 metres in length and satisfies operational requirements, becoming the basis for the Landing Craft, Assault.

Budgets remain tight, and scepticism persists within senior ranks regarding the need for combined operations. Nevertheless, the Inter-Service Training and Development Centre decides to proceed. It orders prototypes of both designs using funds from its £30,000 allocation. Both prototypes are completed within eight weeks.

The Fleming craft undergoes its first trials on the River Clyde. It is then transported to Langstone Harbour near Portsmouth. Here, it is tested alongside the Thornycroft prototype in comparative trials. Captain Maund observes several advantages in the Fleming boat. Troops disembark in one-quarter of the time taken by those in the Thornycroft craft. The Fleming’s silhouette is lower. It creates less surface disturbance at speed and beaches more effectively.

However, the design has two critical flaws. The Birmabright alloy hull acts as a sounding board. Engine noise is extreme. Maund describes the result as ‘terrific’, an overwhelming acoustic signature. This alone undermines tactical surprise. Additionally, the complex hull shape and alloy material make the application of armour nearly impossible.

The Thornycroft design, in contrast, presents practical advantages. Its mahogany planking can be replaced by armour with little difficulty. The slower disembarkation is addressed by lowering the position of the bow ramp. Fore-and-aft bench seating, as used in the Fleming boat, is also adopted to speed up unloading.

The high-profile superstructure, often likened to Noah’s Ark, is revised. It is removed and replaced with a flat deck above the seated troops along the vessel’s sides. This leaves an open central passage, allowing men to run forward and disembark rapidly.

Trials at the Army School of Musketry in Hythe determine the best form of armour protection. Testing accounts for the deflection of bullets off water and the higher muzzle velocity of German small arms, about 60 metres per second greater than that of British rounds. Armour thickness and angle are adjusted accordingly.

The Thornycroft’s engines are also silenced. Modifications ensure they cannot be heard beyond 25 metres in still air. With these refinements, the decision is made to adopt the Thornycroft design as the basis for the Landing Craft, Assault. The Director of Naval Construction and Thornycroft work together to refine the design. Their efforts result in a third prototype: Assault Landing Craft No. 2.

In April 1939, the Admiralty orders eighteen Landing Craft, Assault from Thornycroft. These early models weigh over nine tons and have flush-decked hulls. An armoured bulkhead surrounds the starboard-side steering position, extending roughly sixty centimetres above deck level. Eight more Landing Craft, Assault are ordered in September. Power comes from Thornycroft’s marine conversions of the Ford V8, which are water-cooled petrol engines delivering 65 horsepower each. These engines turn two-bladed propellers through a 41:20 gear reduction. With a load of 3,800 kilograms, the craft reach 10.5 knots at 2,800 revolutions per minute. Later versions use three-bladed propellers.

In March 1940, the Admiralty places an additional order for thirty Landing Craft, Assault. Thornycroft, overwhelmed by commitments to larger naval vessels, subcontracts the work to small yacht-builders along the south coast. Several Landing Craft, Assault, specifically numbers 24 to 29 and 51, receive Parsons conversions of the Ford V8. These have a 2:1 gear reduction and achieve speeds of 12 knots at 3,300 revolutions. The standard engine for most craft becomes the Scripps marine conversion of the same Ford V8. Trials with unladen boats show these engines consistently produce speeds of 11 knots at 2,800 revolutions per minute.

By June 1940, following limited successes in Norway and the evacuation at Dunkirk, forty-eight Landing Craft, Assault are on order. At this stage, Britain faces the imminent threat of invasion. The Assistant Chiefs of Staff focus on homeland defence. They recommend that, due to urgent naval needs, no priority should be given to Landing Craft, Assault then under construction. They also advise halting further production. In their view, landing craft are not immediately vital to the war effort.

This position conflicts with Winston Churchill’s strategy. At the same moment, he establishes the Combined Operations organisation under Admiral Sir Roger Keyes. By July 1940, the number of Landing Craft, Assault on order has risen to ninety-three. At the same time, the Landing Craft, Motorised is still considered useful for large-scale operations, with 106 ordered.

Thornycroft continues to construct many of the Landing Craft, Assault, but other builders soon join the effort. These include yacht-builders such as Camper & Nicholsons of Portsmouth. Thornycroft expresses frequent concern about labour demarcation between companies and their numerous subcontractors.

By early December 1941, plans call for a total of 500 Landing Craft, Assault, with eight more to be ordered each month. The programme expands rapidly in 1942, after more than 200 have already been delivered. To meet demand, non-marine firms are brought in. These include joiners and furniture manufacturers.

One of the most prominent is Harris Lebus, a well-known furniture company located on the River Lea in North London. This site enables completed Landing Craft, Assault to be launched directly into the river. Some of the craft built by these non-specialist firms leak initially, but the overall quality proves acceptable.

Women undertake a significant portion of the construction work in these companies. In total, 1,929 Landing Craft, Assault are built during the war, alongside several types of support landing craft.

Reported speeds and endurance for the Landing Craft, Assault vary by source. By 1945, the fully loaded craft weighs around 13.5 tons, due to extra armour and increased infantry equipment. As with all wooden boats, water absorption over time adds further weight and reduces performance. Equipment and crew standards also evolve. The era of isolated raids gives way to mass amphibious invasion requiring entire flotillas.

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Description

The Landing Craft, Assault is shaped with both function and seakeeping in mind. Its curved deck and upward bow, known as the ‘sampan’ style, enable smooth beaching on varied shorelines. The hull narrows towards a flat bow fitted with a wide ramp, allowing two lines of troops to disembark. The sharp corners and chine construction reflect Thornycroft’s high-speed boat design heritage.

Wooden runners beneath the hull help it lie level when grounded. The outward sloping sides offer better stability if the boat heels. A flat stern houses protected propellers. The front ramp is raised or lowered with internal pulleys, and beach retraction is eased by rollers.

Troops embark through armoured bow doors into a compartment that runs over half the boat’s length. Three benches accommodate the soldiers. The centre bench is removable for cargo. The steering position lies on the starboard side, armoured and low, giving the coxswain clear forward vision while remaining protected.

The coxswain operates using a wheel, telegraphs, gear levers, and a voice pipe. Later versions add radio and non-magnetic armour for navigation. Opposite, an armoured Lewis or Bren gun position offers forward and anti-air defence. Together with the steering shelter and bow doors, these create a continuous protective barrier.

At the rear of the troop deck, a bulkhead separates the engine room. A hatch provides access to the stoker. The afterdeck houses the engines, anchor windlass, and stern gear, protected by a low breakwater and roller gear for anchor operation.

The craft is built mainly from African mahogany, with other timbers used where needed. Its keel is 11.4 centimetres wide, made from Canadian rock elm. The boat measures 11.8 metres long and is framed with 24 wooden ribs spaced 46 centimetres apart.

The hull is covered with two diagonal layers of planking. Planks are 1.27 centimetres thick on the sides and 1.9 centimetres on the bottom. Fastenings include copper rivets, brass bolts, and screws. Steel armour arrives pre-cut and must be fixed precisely. Side armour is 6.4 millimetres thick, running from the bow to the engine compartment.

Engine-room armour is initially removed to save weight but later reinstated due to battle losses. Eventually, troop-deck armour is also added for better protection.

Two Ford-derived Scripps V8 engines power the craft, one on each side of the engine room. Each has a 295-litre petrol tank beside it. The stoker sits between the engines, monitoring gauges and taking orders via telegraph and voice pipe.

The engines are angled slightly downwards to maintain a shallow draught. Beneath them, the hull forms a semi-tunnel shape. Air intake and exhaust systems vary slightly. Exhaust gases exit through the stern, passing through a compartment with rudder controls and flotation material.

Twin rudders provide manoeuvrability and are linked by a connecting rod. Iron guards protect both rudders and propellers. The anchor, made by Duerr, weighs 20 kilograms and is slung centrally between the rudders.

The Landing Craft, Assault is launched using davits or cranes. Fixed and foldable slinging points are positioned near the engine room and coxswain’s station. Crane lifting uses four hull-mounted slinging points. Deck cleats allow for conventional mooring.

Ropes are fixed along the sides to aid personnel in the water. Rough sea launchings prove difficult, prompting the addition of retaining plates and later, improved sling gear with disengaging hooks and alignment bars.

Early craft are painted black inside, with service grey above the chine and enamel coatings below the waterline. In 1941, this colour scheme proves effective in Greece. The 1942 camouflage pattern includes a white bow and upper features, dark grey deck, and blue-grey side patterns. A ‘V’ shape distorts the bow’s outline.

The crew of a Landing Craft Assault typically consists of four Royal Navy personnel, led by a petty officer coxswain. Here is the usual composition:

1. Coxswain (Petty Officer). In command of the craft. Responsible for navigation, steering, and overall control of the LCA during operations, including beach landings under fire.
2. Stoker/Engine Room Rating. Operates and maintains the engines. Located in the engine compartment amidships.
3. Bowman. Handles the bow ramp and assists with mooring and beaching. He helps secure the craft on landing and supervises the disembarkation of troops.
4. Sternsheetsman. Assists with steering when needed, mans the stern, and handles mooring or defensive duties.
5. Signalman (Optional). Responsible for visual signalling using flags or Aldis lamps, particularly when operating as part of a flotilla.
6. Gunner or additional seaman (Optional). May operate a mounted machine gun or help with beaching and recovery in combat zones.

Craft identification is formalised with white-outlined letters and numbers on the bow. During the Sicily landings, extra boards are used to help formations. However, these are soon discouraged to avoid confusion.

For the Normandy invasion, Landing Craft, Assaults are given precise deployment numbers known as Landing Table Index Numbers. These ensure each craft arrives in the correct order during the beach assault.

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Versions

Landing Craft, Support (Large)

To address the need for heavier fire support, the Landing Craft, Support (Large) Mark 1 is developed. Thornycroft again leads the design. This new version is 1.8 metres longer than the medium craft and weighs almost 25 tonnes. It is designed for lifting by derrick rather than davit, similar to Landing Craft, Motorised. It is not completed until April 1943. By then, its 2-pounder gun is outdated for anti-tank use.

Shipborne support craft are now reaching their limits. Future support roles shift to shore-to-shore landing craft, primarily based on the tank landing craft hull. As Landing Craft, Flak, these vessels carry medium and heavy anti-aircraft guns. As Landing Craft, Gun, they may mount 4.7-inch naval guns, 25-pounder field artillery, or multiple 20-millimetre Oerlikons. As Landing Craft, Rocket, they unleash large salvos during the assault phase.

This is part of a growing arsenal of heavy support assets. Naval gunfire is available, from battleships with 406-millimetre guns to corvettes with 102-millimetre guns. However, warships cannot approach closely. Guns over 152-millimetre cannot fire within 460 metres of friendly forces, and those over 203-millimetre must remain 915 metres distant. Therefore, assault forces still require their own gunfire support. The Landing Craft, Gun (Medium) retains its value into 1945.

Laying smoke is considered a primary function of the Landing Craft, Gun (Medium), but it is rarely used in practice. A June 1943 manual admits that knowledge of smoke in combined operations remains mostly theoretical.

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Landing Craft, Assault (Hedgerow)

The Landing Craft, Assault (Hedgerow) variant is developed to clear beach obstacles. It carries a reduced version of the Hedgehog mortar used by anti-submarine vessels. A June 1943 report states the purpose:

“This is a spigot mortar weapon fitted in a Landing Craft, Assault, with the object of clearing blast-actuated anti-tank mines and wire during the first assault wave.”

Each Landing Craft, Assault (Hedgerow) carries twenty-four bombs. One salvo clears a lane 110 metres long and 9 metres wide. However, its effective range is only 90 metres from the bow. Officers demand longer ranges and variable firing positions. Trials at Studland Bay in December 1943 produce mixed results. The weapon performs well against barbed wire but is less effective against German mines.

Each Landing Craft, Assault (Hedgerow) has a crew of four: coxswain, gunner, mechanic, and spare hand.

Despite a few successes in landing operations, the overall performance is disappointing. Some boats suffer structural damage from their own weapons. The design proves unsuitable for rough seas or sustained bombardment. Compared to the massed firepower of rocket-firing landing craft, the Landing Craft, Assault (Hedgerow) is limited in effect.

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U.S. Ranger Mortar Firing Landing Craft, Assault

For the Pointe du Hoc operation to succeed, the Rangers must ascend the cliffs at Pointe-du-Hoc quickly. Fortunately, Combined Operations Headquarters (COHQ) has prepared for this task. It maintains a Department of Miscellaneous Weapons Development under Captain Francis W. H. Jeans of the Royal Navy. Jeans is a seasoned naval engineer and previously served as Assistant Director of Naval Ordnance between 1936 and 1937.

Since cliff assaults are common in Commando raids along the Atlantic coast, the department has developed multiple climbing devices. By 1944, nine such inventions exist. Two of these are particularly relevant to the Rangers.

The first is a rocket-propelled grapnel hook system with attached ropes or ladders. Each device uses a 50-millimetre “J” rocket with a grapnel hook at its head instead of an explosive. The rocket launches from a J-projector at a 45-degree angle. It is connected to either plain rope, toggle rope, or rope ladders.

Toggle ropes have small wooden crosspieces for handholds. Rope ladders offer better grip than plain rope. However, plain rope is lighter, making it easier to launch to greater heights. The ropes are up to 82 metres long. This is sufficient for the Pointe-du-Hoc cliffs.

Initial tests fire the rockets from a small dory offshore. To adapt the equipment for D-Day, Jeans’ department creates Project Scam. Under Project Scam, each Ranger assault craft, British Landing Craft, Assault, is fitted with six J-Projectors. These rocket launchers are arranged in three pairs per vessel. Each pair is mounted along the gunwales at the bow, amidships, and stern, on both port and starboard sides.

The launchers are electrically wired to fire in tandem from a single control at the rear of the craft. This allows two rockets, one on either side, to be fired simultaneously for stability and balance. The distributed placement ensures that ropes can reach a wide portion of the cliff face. It also prevents a single enemy strike from disabling all lines at once.

Each J-Projector is a tubular launcher, angled upward and outward. As the Landing Craft, Assault, approaches Pointe du Hoc, the coxswain or designated crewman fires the rockets in sequence. The rear pair fires first upon touchdown, followed by the others in rapid order.

By the time the landing ramp drops, several ropes are expected to be hanging down the cliff face, ready for immediate ascent. Storage is carefully arranged. Each rope or ladder is coiled in a wooden box placed directly behind its corresponding launcher. This ensures a smooth, uninterrupted feed as the rocket travels skyward.

Grapnel hooks are affixed to the rocket by a wire leader. This keeps the rope attached to the rocket base until it strikes the cliff top. Once the grapnel catches, Rangers test the hold by tugging. Climbing begins at once in pre-assigned teams.

In addition to the six mounted launchers, each Landing Craft, Assault, carries two backup rocket grapnels. These are lightweight, hand-held projectors with coiled rope. Rangers bring them ashore for use at the cliff base. If the main ropes fail to catch, a Ranger can launch a replacement manually. This built-in redundancy increases the chance of success, even under poor conditions or enemy fire.

A distinctive feature of Project Scam is the use of three different types of climbing line. Each Landing Craft, Assault, carries two of each. This results in six total lines per craft, two plain ropes, two toggle ropes, and two rope ladders.

The plain ropes are 19-millimetre manila, without knots or rungs. Their light weight allows them to be projected the furthest. Rangers climb them using the hand-over-hand technique. Some tie small loops or use specific training methods to ascend. These ropes offer minimal resistance during flight and are less affected by wind.

The toggle ropes are also 19 millimetres thick, but include small wooden toggles placed at 30-centimetre intervals. These toggles act as grips and steps. They provide better purchase than plain rope, especially when wet. The toggles may also snag on rocks or uneven ground at the cliff edge, increasing the chance of a secure hold.

The rope ladders are made of rope with wooden rungs spaced at approximately 60 centimetres. Some ladders use new synthetic fibres, such as nylon, which absorb less water than hemp. Once secured, they offer the most stable ascent. Multiple Rangers can climb simultaneously using the rungs. However, the added weight can limit how high the rocket throws the ladder, especially if it becomes waterlogged.

Each craft carries two of each type for several reasons. First, redundancy. If one rope fails, whether due to grapnel slippage or enemy fire, the other might succeed. Second, uncertainty. No one knows which method will work best on D-Day. By using all three types, the Rangers hedge against unknown conditions.

Each line has unique advantages. A plain rope flies higher. A toggle rope offers better grip. A rope ladder provides ease of climbing, especially when under load. Having six climbing lines also allows more Rangers to ascend at once. This opens multiple lanes up the cliff and prevents congestion at any single line.

Each team of 20 to 22 Rangers is assigned specific ropes. This ensures all lines are used efficiently and simultaneously. Speed is critical. The faster the Rangers reach the summit, the better their chances of overwhelming German defences.

Two-inch rockets shot from six J-Projectors launched ropes and ladders up the cliffs. Any gaps are filled with the portable backup units carried ashore. The mixed rope strategy is refined through repeated training. By D-Day, the Rangers trust the system. They know that at least some of the ropes will hold, and that is enough.

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