Mulberries artificial harbors in Normandy

Battle of Normandy

Why artificial ports?

During the first days of the invasion, the allied bridgehead must at all costs be fueled by considerable quantities of equipment: arms, ammunition, gas, food, field hospitals, advanced headquarters… It is therefore necessary to control a port (in deep water if possible to permit the use of large vessels), in order to supply troops.

Image : Construction des éléments Whales en Angleterre Construction of Phoenix elements in England. Photo: IWM

But this part of Normandy offers only two deep-water ports: Le Havre and Cherbourg. These two ports are far from the landing areas and that of Cherbourg will be under allied control only 8 days after D-Day, according to the assault plan.

During this long week, the bridgehead must be consolidated by all means, hence the idea of Lord Mountbatten, a prestigious English sailor, responsible for the creation of two transportable artificial ports

That could be assembled in record time on two beaches of Normandy. Operation code name: “Mulberry”.

Image : Des garde-côtes Britanniques croisent devant Arromanches, épargnée par les combats British coast guards crossed in front of the village of Arromanches, spared by the fighting. Photo: IWM

Mountbatten, with a handful of Anglo-American engineers, decides in a limited time to study the problem. 230 huge concrete caissons called “Phoenix” were imagined. Assembled together to form a 7 km long arc of a circle, these caissons are forming a breakwater to protect against currents and storms.

Image : Installation des jetées permettant le déchargement du matériel de guerre Installation of piers for the unloading of war material. Photo: IWM

The interior of this arc is supposed to be as calm as a lake and thus boats can be able to unload their cargoes on the floating landing stages which are called “Lobnitz” at all times.

These platforms follow the tides thanks to a system of pylons located at the four corners of the jetties which allow the platform to go up and down according to the level of the sea. Thus, the unloading can be carried out every hour. These pontoons measure 60 by 18 meters.

Image : Eléments Phenix servant de brise-lames, surmontés d'une tourelle de DCA (Défense Contre Avions) Phoenix elements used as breakwaters, surmounted by an anti-aircraft turret. Photo: IWM

The “Phoenix” caissons, of varying sizes, the largest of which measures 60 meters long and 20 meters high, are mostly topped by an anti-aircraft turret to protect the port from enemy air attacks. Cargoes, when unloaded on platforms, are transported on land by vehicles that use floating piers. Three platforms are planned, two of which are designed for a one-way traffic.

Image : Eléments Phenix servant de brise-lames, surmontés d'une tourelle de DCA (Défense Contre Avions) Phoenix elements used as breakwaters, surmounted by an anti-aircraft turret. Photo: IWM

All the necessary elements are produced in order to assemble two Mulberries, one located at Arromanches (Mulberry B), the other at Saint-Laurent-sur-Mer (Mulberry A). The towon of Arromanches was mostly untouched by the bombing of naval artillery on D-Day and no landing was made in front of this locality in order to simplify the work required by the military Engineer to install the elements of the artificial harbor.

Implementation of these artificial ports

The “Phoenix” caissons, the “Lobnitz” platforms and the floating piers are towed one by one on the English Channel. The tugboats, arriving at sight of the coast in the morning of June 6, receive the disastrous calls and radio reports from American soldiers trampling on Omaha Beach. For a moment, they believe that the landing is a failure.

Image : Un char Sherman rejoint la terre ferme en empruntant une des cinq jetées du port artificiel d'Arromanches A Sherman tank on one of the five piers of Arromanches artificial harbor. Photo: IWM

On the evening of D-Day, in the area of Arromanches, which was mostly protected from infantry and artillery fire, the first ships to serve as breakwater elements (codename: “Gooseberries”) arrive in position and are sunk the following days. Then, at Saint-Laurent-sur-Mer as at Arromanches, the two artificial ports are assembled.

The storm

But the fall of Cherbourg takes longer than expected and the allies still use the 2 harbors eight days after D-Day. A strong storm, on June 19, destroyed the port of Saint-Laurent-sur-Mer which is irreparable. That of Arromanches has suffered many damage but is easily repairable; it will operate alone for a month, discharging nearly 10 thousand tons of material per day.

Image : Destructions causées par la tempête du 19 juin 1944 Destruction caused by the storm of 19 June 1944. Photo: IWM

On 26 June, resistance in the town of Cherbourg ceased, but sporadic resistance in the arsenal continued: the fighting ended in northern Cotentin from the 1st of July. the port facilities were immediately restored and the first allied transport ship entered the deep-water port of Cherbourg on 17 July 1944.

Image : Vue aérienne du port artificiel d'Arromanches Aerial view of the artificial port of Arromanches. Photo: IWM

For Mountbatten and his engineers, it is mission accomplished, and with it the most gigantic project of the landing of Normandy, having asked for the greatest technical prowess. Its vestiges can still be seen today at Arromanches and also in Saint-Laurent-sur-Mer at low tide.

On June 12, 1944, more than 300,000 men, 54,000 vehicles and 104,000 tons of supplies were landed at Arromanches. Throughout the Battle of Normandy and for the two artificial ports: two and a half million men, 500,000 vehicles, and 4 million tons of material transited through Mulberries A and B. During the last week of July 1944, traffic is at its best with 20,000 tons per day. Mulberry B harbor of Arromanches is used until November 19, 1944.