What happened at arromanches?

Answer 1

Rough Channel seas and a tide that rises and falls twenty ft meant that equipment put down on the flat Normandy beaches would be swamped by the tide before it could all be moved onto dry land. And the idea of starting off the invasion by capturing one of the heavily defended French ports was out of the question, it would take too long. The story goes that one of the officers involved in the planning, remarked casually to one of his colleagues, not intending to be taken seriously, "Well, I suppose we'll have to take our harbours with us." This remark started the experts on a train of thought that ended at the point where the ramps of the prefabricated ports touched the Normandy shore. On D-Day a huge fleet of several nationalities, besides British and American, began to tow the ports across the English Channel to pre-arranged sites on the French shore, escorted by the British Navy. On arrival, American Seabees, British Sailors and British Army Engineers assembled them.

20,000 British workers were assigned to building the parts at various points in England. (865,000 tons of reinforced concrete had to be cast in six months)

In the first 109 days of the invasion the Allies put ashore 2,500,000 troops, more than half a million vehicles, and 17,000,000 ship tons of munitions, weapons and supplies - a task that could not possibly have been achieved without the portable harbours.