ARROMANCHES-LES-BAINS

Mulberry Harbour
The Engineering That Won D-Day

Region: Normandy (Calvados)
Article Type: WWII logistics + engineering innovation + present-day reflection

Opening Scene

Morning tide slips around scattered giants of concrete.

They sit offshore like patient monuments, weathered and immovable.

Seagulls circle. Waves tap gently against stone. The shoreline of Arromanches-les-Bains feels almost delicate now.

Yet in the summer of 1944, this quiet stretch of sand handled more cargo per day than many of Europe’s established ports.

The contrast is immediate.
Today, a small seaside town.
Then, an industrial artery of invasion.

Where holidaymakers now photograph sunsets, engineers once assembled a harbor from nothing.

Why the Mulberry
Harbour Was Necessary

D-Day was never only about landing troops.

The assault on June 6, 1944 placed Allied soldiers ashore. But placing an army and sustaining it are entirely different challenges. Ammunition. Fuel. Vehicles. Food. Medical supplies. Reinforcements.

The Allied command understood a brutal truth:
Without a functioning deep-water port, the invasion would stall.

Every major French harbor was heavily fortified. German forces expected any port to be a primary objective. Capturing one intact was unlikely. Destroyed docks would delay operations for weeks or months.

And delay meant vulnerability.

The planners concluded something audacious:
If they could not capture a port, they would build one.

The Engineering Concept

The Mulberry system was not a single structure but a choreography of components:

• Phoenix units – enormous prefabricated concrete
caissons

• Whale bridges – floating steel roadways connecting
ships to shore

• Gooseberries – lines of deliberately sunk ships
forming outer breakwaters

• Additional floating piers and anchoring systems

These elements were constructed in Britain in complete secrecy. Concrete was poured into massive molds. Steel spans were engineered with flexibility to withstand tides.

Then, in one of the most remarkable logistical movements of the war, the pieces were towed across the English Channel.

Two artificial harbors were assembled:

• Mulberry A at Omaha Beach
• Mulberry B at Arromanches

Within days of assembly, thousands of tons of supplies were landing daily. Trucks rolled continuously off floating piers onto Norman sand.

It was not spectacle. It was systems engineering under pressure.

The Great Storm:
June 19–22, 1944

Just two weeks after D-Day, the English Channel unleashed a violent storm.

For three days, waves battered the fragile artificial harbors.

Mulberry A, off Omaha Beach, suffered catastrophic damage. It was abandoned.

At Arromanches, Mulberry B absorbed punishment but endured.

The difference altered the campaign.

For months afterward, Arromanches functioned as the primary logistical hub of the Allied advance. By autumn 1944, more than two million men, hundreds of thousands of vehicles, and millions of tons of supplies had passed through Normandy.

Engineering resilience had become operational advantage.

Arromanches Today

Copyright: Sabrina Lorkin
https://en.normandie-tourisme.fr/
unmissable-sites/arromanches/

At low tide, Phoenix caissons still rise from the water like fractured battlements. Some sit close enough to shore to study their scale. Others linger farther out, softened by decades of salt and wind.

The Musée du Débarquement stands overlooking the harbor, explaining in meticulous detail how the system worked. Diagrams, models, archival footage.

Above town, the circular cinema known as Arromanches 360 offers panoramic reflections on the Battle of Normandy, the modern landscape layered over wartime memory. The town itself feels gentle. Cafés. Seafront walks. Families on the sand. But the geometry offshore remains unmistakable. Concrete, placed with purpose.

The town itself feels gentle. Cafés. Seafront walks. Families on the sand.

But the geometry offshore remains unmistakable.

Concrete, placed with purpose.

Why It Matters

Arromanches shifts the narrative of D-Day.

Omaha speaks of courage.

Utah speaks of adaptation.

Pegasus Bridge speaks of precision.

Arromanches speaks of sustainability.

Victory required not only bravery, but calculation. Not only assault, but anticipation.
The Mulberry Harbour demonstrates that wars are often decided by what happens after the first shot is fired.

Logistics becomes strategy.

Engineering becomes warfare.

Preparation becomes power.

Standing on this shore, the sea appears calm. The concrete remains do not shout.
They endure.

And that quiet endurance tells its own story.

Sources & Further Research