It’s 6 June 1944, Normandy: D-Day. The camera sweeps through the French countryside and into the coastal village. Down a narrow side street, there’s a glimpse of a convoy of army trucks and jeeps, trundling along a jetty that stretches far out to sea. The seafront is a hive of activity with supplies, vehicles and soldiers everywhere. The camera soars over the rooftops to give a panoramic view. 

For the first time, it’s possible to clearly appreciate the scale of one of the Second World War’s greatest engineering feats – a complete harbour, built only days after the largest seaborne invasion the world has ever seen. The Mulberry Harbour at Arromanches in Normandy is the staging point for the beginning of the end for Hitler and Nazi Germany.

It’s 70 years since the engineers behind the Mulberry looked on as it was assembled from thousands of pieces floated across the English Channel. Incredibly, today, sitting in a 3D theatre on the outskirts of Paris, we can share that view via a stunningly real computer simulation that painstakingly recreates the event with the same software that engineers use to design modern products and vehicles.  

The 3D recreation is a project by French software company Dassault Systèmes and, admittedly, part-marketing showcase for the capabilities of its Catia and Solidworks 3D CAD software. Astutely, Project D-Day is being publicised to coincide with the event’s 70th anniversary.

But the project also has merit as a social endeavour. At the real Arromanches, in June 2014, the remnants of the Mulberry Harbour are slowly being eroded by the sea. So, too, are the memories of the innovative designs and feats of engineering that enabled D-Day. Underneath the marketing sheen, there’s a commendable effort to not only commemorate the engineers’ contributions during the war, but also to preserve their innovative designs and the modern-day technologies born from them.  

Nicolas Serikoff, the specialist in charge of Dassault’s D-Day project, believes that many records of the innovations and designs have already disappeared. “Today’s 3D digital mock-ups preserve that industrial memory, so we’ve initially aimed to develop several of the iconic machines from D-Day. 

“It’s a real tribute to the engineers of D-Day who made it happen.”

For the project, researchers from Dassault set about accumulating film, blueprints, plans, microfilm and photography so that they could reverse-engineer the Mulberry and two vehicles used on D-Day – the CG-4A Waco-Glider and the LCVP personnel carrier. That was the boat made famous in the opening
scenes of Saving Private Ryan.

The largest part of the project was a full 3D recreation of the Mulberry B part of the artificial harbour, which was devised by engineers as a way to quickly deploy a harbour because all the existing ones were heavily occupied.

The Mulberry comprised around 10 miles (16.1km) of 80ft (24.4m) wide steel roads that rested on concrete or steel pontoons and could carry up to a 40-tonne Sherman tank.

These roads connected the beach to floating pier heads out at sea, where ships could berth and unload supplies. Huge, reinforced-concrete caissons were laid in a semicircle around the harbour, to protect it from the tides and storms. 

The pier heads were unique in that they were on vertical legs, and could partially lift out of the water when the tide went out. They would then float, thanks to cabling and a specially designed kite-anchor that dug itself deeper into the seabed when the cable was pulled. This aspect of the design meant that ships could unload vital supplies, using cranes, around the clock. 

During the installation of the harbours in 1944, the engineers lived on ships, 2km away from the shore. Once the beaches were secure, tens of thousands of pieces of Mulberry A and B were floated into place in a matter of days. Although the roads were designed to withstand rough seas and twist up to 45º, Mulberry A was hit by a terrible storm on 19 June, resulting in the wrecking of 800 vehicles. Mulberry B at Arromanches survived, and became the world’s busiest port in terms of traffic volume during the war.

Mulberry B was recreated using the original plans, photos and construction manuals from the Royal Engineers Museum in London. The Mulberry roadways were designed by Major Alan Beckett of the Royal Engineers, who says the original project’s far-reaching influence is still felt by engineers today.

“In several schemes, we use the inspiration of Mulberry,” says Beckett. “We didn’t have the budget or time constraints they had, but nevertheless there are plenty of lessons here for today’s engineers.

“There are lots of innovations that are still used today, like floating caissons. Roll-on/roll-off ferries were pioneered here. Jack-up pontoons are used widely by contractors nowadays, and floating roadways are also still used today.”

Beckett’s son, Tim, is a consulting engineer in the marine sector and an adviser on the current project. “The recreation shows you how huge this harbour was – it’s the size of Dover Harbour – all the main elements were done in a week.” 

After the Mulberry, researchers set about reverse-designing the vehicles to populate the recreation. The first to be turned into a 3D model was the CG-4A Waco-Glider. This aircraft was made of wood and fabric, and designed to break up if it hit an obstacle. They were used to land soldiers covertly behind enemy lines before the beach assault, to secure key infrastructure further inland. Travelling at 90mph, they could carry 12 men or a jeep. They were towed across the channel by C47 aircraft and then cut loose. All the original gliders that were made have since disintegrated.

However, sourcing blueprints of the aircraft proved problematic. The original plans had been scanned into computers inadequately, and dimensions and lists of components hadn’t been preserved. Mehidi Tayoubi, vice-president of digital and experiential strategy at Dassault, explains: “We noticed quickly that it was hard to find blueprints, and that you lost a lot of detail when they were digitised. The plan now is for the project to be ongoing and for all the information to be gathered and preserved slowly, as a homage to the engineers that made it possible.”

Engineers used a variety of different data sources – including laser scanning a replica from a museum in the US and integrating those dimensions into the simulation – to digitally recreate the 3D model of the Waco-Glider in Catia. 

The aircraft can now be flown in a computer simulation, accurately recreating the flight controls, physics and environmental controls. The 3D models contain fully working 3D representations of the mechanical systems and all the parts, down to the screws and bolts.

The second vehicle digitally recreated was the Landing Craft Vehicle Personnel (LCVP), a boat made almost entirely of wood, to land troops on the beaches. More than 15,000 LCVPs were made in New Orleans by Higgins Boat Industries. It based the design on boats used in the Bayou swamps, with additional features including a metal front ramp that opened quickly when they hit the beaches. The hull, rudder and propeller of the LCVP were carefully designed so that it could land and manoeuvre in shallow water – the Normandy D-Day beaches have a depth of just one metre. Serikoff says that 3D models revealed the clever design of a smaller second rudder on the hull, which allowed the boat to be reversed out of the shallow water.

Translated into a modern medium by the CAD tools of today, the ingenious constructions of the engineers behind the Normandy landings can be seen more clearly, and the scale of their achievements appreciated anew. The project also preserves detailed engineering plans for future generations to reference online and in museums. It’s a fitting homage to those who gave so much for their country, and tells a thrilling story in a format that future generations will understand. 


Skeleton key: The glider and landing craft were recreated from original blueprints