The battle for control of the seas, with both Britain and Germany seeking to blockade each other had begun on the very first day of war. In Britain, the tonnage of shipping lost and the amount of goods entering the country were closely monitored and the subject of weekly review at Cabinet level. The U-Boat menace was now of increasing concern to Churchill.
Unless more effective action was taken to protect convoys of merchant ships coming to Britain then the ability to continue the war, even to feed the population, would be threatened. Churchill, as Minister of Defence, set out his priorities for action in his famous memorandum of 6th March. From now on the the overall campaign had a name – ‘The Battle of the Atlantic’ – and a range of measures to step up the fight were pressed forward by Churchill:
THE BATTLE OF THE ATLANTIC
Directive by the Minister of Defence, March 6, 1941
In view of various German statements, we must assume that the Battle of the Atlantic has begun.
The next four months should enable us to defeat the attempt to strangle our food supplies and our connection with the United States.
For this purpose –
1. We must take the offensive against the U-boat and the Focke-Wulf wherever we can and whenever we can. The U-boat at sea must be hunted, the U-boat in the building yard or in dock must be bombed. The Focke-Wulf and other bombers employed against our shipping must be attacked in the air and in their nests.
2. Extreme priority will be given to fitting out ships to catapult or otherwise launch fighter aircraft against bombers attacking our shipping. Proposals should be made within a week.
3. All the measures approved and now in train for the concentration of the main strength of the Coastal Command upon the northwestern approaches, and their assistance on the East Coast by Fighter and Bomber Commands, will be pressed forward. It may be hoped that, with the growing daylight and the new routes to be followed, the U-boat menace will soon be reduced. All the more important is it that the Focke- Wulf, and, if it comes, the Junkers 88, should be effectively grappled with.