On the day before war was declared the Royal Air Force flew to France a small advance party of eighteen officers and thirty-one other ranks. By the 27th September the Royal Navy with shipping of the Mercantile Marine under their control had moved to France, without the loss of a single life,.
Thereafter the build-up of our forces and of equipment, stores and supplies continued steadily. Advance parties sailed from Portsmouth on the 4th of September, and the first convoy of troopships left Southampton and the Bristol Channel ports on the 9th. The first main landings took place at Cherbourg no the 10th and at Nantes and St Nazaire two days later. Thereafter convoys bearing men and material followed at frequent intervals. In their naval war plans, issued in May , the Germans recognised that they would 'be excluded from the Channel in a very short time'.
And during the first three weeks of September, when Hitler still hoped to avoid immediate war with the Western Power, the action of German submarines was accordingly limited by his orders. After that date the restrictions were progressively removed. While foresight and careful planning had their reward in the smoothness with which the Royal Navy's plans worked, the effectiveness of security measures was thus proved by the enemy's mistaken action.
All this, and all the going and coming which was to follow, was made possible by the completeness of the Navy's control of the narrow seas and of their approaches. Almost from the start rolling-stock and loaded wagons had been sent by train ferry direct to Calais and Dunkirk, and Dieppe had been used as a medical base; but the carriage of all reinforcements and stores to the western ports of France placed a severe strain on shipping resources and escort forces, and it quickly became apparent that for military as well as naval reasons it was desirable to make fuller use of the French Channel ports and so reduce both the sea passage and the overland carry.
The French were anxious to avoid action which might invite air attacks on these ports and would not at first agree to their use, but in October they acquiesced; a start was made by sending cased petrol direct to Caen, and in the following month a base was opened at Havre. One further factor which certainly contributed to the continued safe passage to France of men and stores was the Navy's closing of the English Channel by a mine barrage across the Straits of Dover.
