The Mole Seaport at Zeebrugge, December 1918: The World’s Longest Breakwater

The Mole Seaport at Zeebrugge, photographed here in December 1918, stands as one of the most remarkable engineering achievements of the early 20th century.

Deepwater Seaport Built for the Modern Age

Opened in 1903 by King Leopold of Belgium, this vast deep-water harbour was built to withstand the harsh conditions of the North Sea. Its defining feature — a crescent‑shaped concrete Mole stretching 1.5 miles into the water — remains the longest structure of its kind in the world of the time. Today, Zeebrugge has grown into a chief industrial port, but its beginnings lie in this monumental construction that once dominated the Belgian coastline.

The image shows evidence of damage after the raid. See the rubble lining the foot of the mole wall and a disused gun to the left. This photo was purchased from a flea-market to form part of the Zeebrugge collection. It is the original photo and is unlikely to be seen in mainstream published books or articles on the Web.


The Mole at Zeebrugge is the Longest of its kind in the world at the time.

A 1.5‑Mile Crescent‑Shaped Breakwater Facing the North Sea

This deepwater seaport at Zeebrugge was built in the early part of the 20th century and today is a heavily industrialised port. Indeed, the Mole was opened with some pomp by King Leopold of Belgium in 1903. This photograph was taken fifteen years later in 1918.

At the time, this construction represented a big step forward in maritime infrastructure, designed to protect the harbour from the violent storms that swept in from the west. Its construction allowed Zeebrugge to function as a major deepwater port capable of accommodating large vessels, essential for Belgium’s blossoming industrial and commercial ambitions.

The massive construction is crescent-shaped and juts 1.5 miles out to sea, pointing in a north-easterly direction towards the North Sea.

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HMS Intrepid scuttled in the Mole

Aerial view of scuttled ships Intrepid and Iphigenia

German naval officers at Ostend

Gun emplacement on the Mole coastline

Gun in camouflage on the Mole

German Guns in Camouflaged Bunkers off the Coast of Zeebrugge

This remarkable photograph shows a line of German coastal guns placed within wicker‑covered bunkers along the coast near Zeebrugge during World War I. With the coastline visible to the left and the barrels pointing seaward, these weapons formed part of the formidable defensive network that protected the approaches to the Bruges Canal and the Zeebrugge Mole.

Rare Photo of German Guns on the Coast

Designed to repel Allied naval attacks, these guns were spaced roughly fifty yards apart, each housed in its own reinforced concrete emplacement. Three guns are clearly visible in the image, with a fourth just discernible in the distance — a reminder of the scale and density of the German coastal defences. Notice the rosters on the inner wall.

Zeebrugge Guns Camouflaged on the Mole

Why the Germans Fortified Zeebrugge

By 1917–1918, Zeebrugge had become one of the most strategically important locations on the Belgian coast. The harbour and its massive Mole provided the German navy with a sheltered base from which to launch U‑boats and torpedo boats into the English Channel. Protecting this stronghold was essential to maintaining the Flanders flotilla’s operations.

To defend the harbour, the Germans constructed a network of gun batteries, bunkers, searchlights and observation posts along the coastline. These artillery positions were designed to detect and destroy any Allied vessels attempting to approach the Mole or the canal entrance.

Wicker Camouflage: Concealment and Blast Absorption

One of the most striking features in this photograph is the wicker cane encasing each gun. This unusual material served two key purposes:

Camouflage: The woven cane helped break up the outline of the gun and its concrete bunker, blending the structure into the surrounding dunes and coastal terrain. From the sea — especially under low light — the guns were far harder to spot.

Blast Absorption: The wicker may also have acted as a buffer, reducing the impact of nearby explosions and preventing shrapnel from ricocheting around the emplacement.

This combination of concealment and protection made the bunkers more resilient during Allied bombardments.

A Defensive Line Facing the North Sea

The alignment of the guns — all pointing out to sea — reflects their primary purpose: to repel any naval assault on the Mole. Their spacing, roughly fifty yards apart, allowed overlapping fields of fire, creating a deadly barrier for any approaching vessel.

These coastal guns were among the many obstacles that made the 1918 Zeebrugge Raid so perilous. Any ship attempting to land marines on the Mole or approach the canal entrance would have been exposed to intense artillery fire from positions just like these.

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Gun barrel with firing mechanism on the Mole Coast

Views of the Mole Seaport with gun in foreground

Aerial view of scuttled ships Intrepid and Iphigenia

Bomb damaged submarine shelters on the Mole

German naval mechanics on the Mole

Aerial View of the Mole with Scuttled Naval Ships Intrepid and Iphigenia

This remarkable aerial photograph, taken in 1918, shows the aftermath of the Zeebrugge Raid with the scuttled British blockships HMS Intrepid and HMS Iphigenia lying across the entrance of the Mole harbour. This view is from above.

A Rare 1918 Aerial Photograph of the Zeebrugge Mole

These vessels were deliberately sunk during the daring allied assault on St George’s Day 1918, forming part of a bold plan to block the Bruges Canal and disrupt German U‑boat operations along the Belgian coast.

This photograph, taken in 1918, shows an aerial view of the Mole off the coast of Zeebrugge with the scuttled naval vessels HMS Intrepid and HMS Iphigenia during the Zeebrugge Raid.


Scuttle Ships Intrepid and Iphigenia during the Zeebrugge Raid

The Blockship Plan and the Fate of HMS Thetis

The Zeebrugge Raid relied on three end-of-the-line cruisers — HMS Thetis, HMS Intrepid, and HMS Iphigenia — repurposed as blockships. Their mission was to enter the narrow canal entrance and scuttle themselves in place, stopping German vessels from accessing the open sea.

However, the plan did not unfold as intended. HMS Thetis, leading the formation, became entangled in German defence nets stretched across the harbour. Immobilised and under fire, she was unable to reach her designated scuttling point, forcing the remaining ships to continue without her.

Intrepid and Iphigenia Reach the Mole Harbour

Despite intense artillery fire from German gun batteries along the Mole, HMS Intrepid and HMS Iphigenia pushed onwards. Both vessels were laden with concrete to ensure they would sink rapidly and remain immovable once scuttled.

Explosive charges were lit to hasten the sinking. 

Incredibly, the sailors escaped in small motor launches and made their way back to the supporting ship HMS Invincible, surviving what was effectively a one‑way mission.

Closing the Harbour: The Impact of the Blockships

Once sunk, the two blockships created a barrier across the Mole harbour entrance. Their presence temporarily hampered German naval movement, forcing U‑boats and destroyers to seek alternative routes.

However, the obstruction was temporary. Within a short time, German engineers dredged a new channel around the wrecks, restoring access to the Bruges Canal. Even so, the raid had significant symbolic value and was celebrated in Britain as an act of great bravery.

The Ships Behind the Mission

Both Intrepid and Iphigenia were second‑class cruisers weighing around 3,600 tons each. By 1918, they were considered expendable, making them ideal candidates for the blockship operation. HMS Intrepid had previously served as a minelayer, deploying naval mines in earlier stages of the war.

HMS Iphigenia had also seen long service and was nearing the end of her operational life. But their final mission at Zeebrugge ensured their place in naval history.

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German guns in camouflaged bunkers on the Mole
HMS Vindictive prior to scuttling
Scuttled HMS Intrepid and Iphigenia in the Mole
Bomb damaged submarine shelters on the Mole
Bomb damage to the Mole after the Zeebrugge Raid

WW1 Photograph of Gun Emplacement on the Mole Coastline near Zeebrugge

The Zeebrugge Mole was one of the most heavily fortified structures on the Belgian coastline during World War I, and this rare photograph of a heavy gun emplacement provides a detailed view of one of its powerful gun mechanisms.

A Detailed Look at a German Gun Emplacement on the Zeebrugge Mole

Used during the 1918 Zeebrugge Raid, this heavy coastal gun shown in the photograph reveals the intricate engineering behind Germany’s coastal defences — from the reinforced gun shield and breech mechanisms to the precise aiming and firing apparatus.

German inscriptions, partially legible on the metalwork, hint at the gun’s operational capabilities, including illumination settings and elevation adjustments. Once the smokescreen lifted during the raid, weapons like this played a devastating role in targeting British vessels approaching the Mole.

A heavy gun emplacement located on the Mole Coastline

Close‑Up View of the Gun Shield, Breech and Firing Mechanism

A close up view shows in detail the gun shield, the breech sights, positioning mechanism and firing apparatus. The inscriptions in German are in places unclear, but I have managed to translate the parts that are comprehensible. The inscription has been shown enlarged in the photo. See below for the meanings.

Close up view of the inscriptions in German

Translating the German Inscriptions on the Gun

Ableuchten: mean to able lights or to shine a light all over.

Erhoh: Infinitive of the verb erhöhen: which means to increase, raise or enhance. The figure given here is 26.12.

Leuchigurtel: means luminous belt.

Brenni or Drenni: yields no results, but the figure given here is 29 sec.

Nebelstellung: yields no results.

Detail of the firing and aiming mechanism

The Role of Mole Artillery in the Zeebrugge Raid

It could be assumed from the German inscriptions that this particular gun emplacement possessed the ability to shine a light upon the British targets. Once the veering wind had cleared the smokescreen from view, the German forces were able to pick off the British ships. This meant disaster for the Zeebrugge Raid mission.

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German guns in camouflaged bunkers on the Mole

Shredded gun barrel on the Mole

HMS Intrepid scuttled in the Mole

Bomb damaged submarine shelters on the Mole

German naval officers at Ostend

A Heavy Gun on the Zeebrugge Mole: A Rare Glimpse Into WWI Coastal Defences

Imagine standing on the windswept Mole at Zeebrugge in 1918, the smell of smoke still hanging in the air after the British raid. This is what this image encapsulates. 

The Role of Heavy Guns in Coastal Defence

This striking photograph shows a heavy German coastal gun mounted on its concrete base just off the coast of Zeebrugge, Belgium. The location, is part of the Mole — the long, curved breakwater that protected the harbour. Keeping company, were several reinforced bunkers nestled in the landscape, built to withstand both naval bombardment and aerial attack.

The photograph was likely taken by a German naval officer shortly after the British Naval Raid on Zeebrugge on St George’s Day, 1918.


Heavy Mounted Gun on the Mole Coastline

WWI coastal defences

Although the image appears calm, it was likely taken in the tense aftermath of the British Naval Raid on Zeebrugge, carried out on St George’s Day, 23 April 1918. The raid aimed to block the harbour and prevent German U‑boats from using it as a base. The Mole was one of the most heavily defended structures on the Belgian coast, and guns like this one played a crucial role in its protection.

Zeebrugge Mole Heavy Hun

The heavy gun dominates the frame, its barrel fixed toward the sea. The concrete mounting platform reveals the scale of the weapon — designed not for mobility, but for endurance. These guns were intended to fire on approaching ships long before they reached the harbour entrance.

In the close‑up image, the intricate workings of the gun mechanism become visible. Levers, gears, and elevation controls show the engineering precision behind German coastal artillery. Even in stillness, the machinery suggests the noise, heat, and physical effort required to operate it.


Close up View of the Gun Mechanism

An Authentic World War One Photograph

This image was almost certainly taken by a German naval officer or official photographer. Germany employed far more photographers than Britain during the First World War — roughly ten German photographers for every one British counterpart. Their role was to document fortifications, equipment, and daily military life.

A small number of amateur servicemen also carried personal cameras, slipping them into packs despite restrictions. Their photographs often captured candid, unfiltered moments of the war. Tragically, many of these private collections were lost, damaged, or destroyed in the years that followed, making surviving images like this one especially valuable.

A Collectible Photograph from World War 1

Photographs of the Zeebrugge Mole are rare. The area was heavily fortified, access was restricted, and much of the infrastructure was damaged or dismantled after the war. Each surviving image helps historians and enthusiasts understand:

This photograph is more than a record of a gun; it is a fragment of a moment when the outcome of the war at sea was still uncertain.

A Final Reflection

Standing on the Mole today, it is hard to imagine the noise, tension, and danger that once filled this stretch of coastline. This photograph offers a rare window into that world — a reminder of the engineering, strategy, and human effort that shaped the final year of the First World War.


For every ten official German photographers, Britain only had about one. A few amateur servicemen carried cameras in their packs and recorded important war evidence. Sadly, most photographs have been lost or destroyed.

The image close up shows the intricate workings of the gun.

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Bomb damage to the Mole after the Zeebrugge Raid

Views of the Mole Seaport with gun in foreground

HMS Vindictive prior to scuttling

HMS Intrepid scuttled in the Mole

German naval mechanics on the Mole

The Zeebrugge Raid of 1918: The Daring British Assault on the Zeebrugge Mole

The Zeebrugge Raid of 1918 was a British naval operation during the First World War aimed at blocking the German‑held port of Zeebrugge in Belgium. By scuttling old ships at the harbour entrance and attacking the heavily defended Mole, the Royal Navy attempted to disrupt German U‑boat activity in the North Sea.

The Zeebrugge Raid of 1918: The Daring British Assault on the Zeebrugge Mole

On the second half of 1914, the forces of the German army had pushed into Belgium, taking over the town of Zeebrugge. A two mile crescent-shaped outcrop called the Mole had been constructed in order to hamper the British Naval Intelligence from incursions.

Along with nearby Ostend, Zeebrugge with its Mole coastline, provided shelter for German destroyers and torpedo boats. Naturally the British Forces needed to breach the Mole in order to eradicate the U-boat threat.

Aftermath and Legacy of the Zeebrugge Raid

Map of Zeebrugge and the Mole

However, the Mole was defended by a dozen or more strategically-placed German coastal guns, all facing out to sea.

On the 23 April 1918 (St George’s Day) the Royal Navy, the Royal Marines and the Submarine Service gathered servicemen, mostly volunteers, to undertake a daring attack upon the Mole.

The plan was to use a smokescreen under which two old submarines laden with high explosives were to be detonated with the aim of destroying the Mole viaduct shoreline. Then, three old cruisers, HMS Intrepid, Iphigenia and Thetis, all heavily laden with cement, were to be scuttled at the Mole entrance. This would in effect block the entrance to the Mole.

The HMS Vindictive

HMS Vindictive Assault Ship

To act as an escort and armed with a landing party, HMS Vindictive, a six-inch gun second class cruiser had been stripped and reinforced with extra metal protection as a shield for the assault force. Once the Vindictive was alongside the harbour, the landing party was to take out the German gun batteries.

Before the attack even began the wind direction changed, removing the smokescreen. The vessels were sighted from the shoreline. Illumination lights were sent up making the attack an easy target. Not put off, the raid pushed on.

Scuttling the Blockships

HMS Thetis grounded before its proper position had been reached. The Intrepide and the Iphigenia were scuttled. Under intense close range fire, Vindictive’s landing party struggled to get ashore. Although the daring raid on the Zeebrugge Mole was good for national prestige, there had been many casualties. And after a few days, the Mole was operational once more. For the courage displayed, a number of British servicemen were acknowledged with many awards.

Once the war was over, it took a salvage company almost a year to clear the Mole properly. Zeebrugge today is a busy commercial area with its skyline covered by cranes for the loading and unloading of container ships.

The Mole is now a pier and docking area for cruisers.

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