On 8th December 1940, in a wide ranging letter to President Roosevelt, Winston Churchill reviewed the state of the war. Now isolated from continental Europe, Britain’s main source of supply, for food as well as all manner of war munitions, lay across the Atlantic. The Germans had recently had a series of successes, as their Surface raiders and U-Boat wolfpack tactics paid off. British countermeasures were constantly being developed but convoy escorts were not yet well co-ordinated, and there was still no answer to the long range Condor planes being used to spot shipping for the U-Boats.
This letter was copied to the War Cabinet and might well have been intended for a wider audience given the characteristic language employed:
The danger of Great Britain being destroyed by a swift, overwhelming blow, has for the time being very greatly receded. In its place, there is a long, gradually-maturing danger, less sudden and less spectacular, but equally deadly. This mortal danger is the steady and increasing diminution of sea tonnage.
We can endure the shattering of our dwellings, and the slaughter of our civil population by indiscriminate air attacks, and we hope to parry these increasingly as our science develops, and to repay them upon military objectives in Germany as our Air Force more nearly approaches the strength of the enemy.
The decision for 1941 lies upon the seas. Unless we can establish our ability to feed this Island, to import the munitions of all kinds which we need, unless we can move our armies to the various theatres where Hitler and his confederate, Mussolini, must be met, and maintain them there, and do all this with the asurance of being able to carry it on till the spirit of the Continental Dictators is broken, we may fall by the way, and the time needed by the United States to complete her defensive preparations may not be forthcoming.
It is therefore in shipping and in the power to transport across the oceans, particularly the Atlantic Ocean, that in 1941 the crunch of the whole war will be found. If, on the other hand, we are able to move the necessary tonnage to and fro across salt water indefinitely, it may well be that the application of superior air power to the German homeland and the rising anger of the German and other Nazi-gripped populations, will bring the agony of civilization to a merciful and glorious end.
But do not let us underrate the task.
However, there was one crucial factor that he had to spell out.
The moment approaches [he said] when we shall no longer be able to pay cash for shipping and other supplies. While we will do our utmost, and shrink from no proper sacrifice to make payments across the Exchange, I believe you will agree that it would be wrong in principle and mutually disadvantageous in effect, if at the height of this struggle, Great Britain were to be divested of all salable assets, so that after the victory was won with our blood, civilisation saved, and the time gained for the United States to be fully armed against all eventualities, we should stand stripped to the bone. Such a course would not be in the moral or the economic interests of either of our countries.
See TNA CAB/66/13/46
The number of ships sunk and the rate of supplies entering Britain was given close attention at the highest level. The weekly Naval Situation report to the War Cabinet would give a broad overview, as well as listing all the individual ships sunk. The general summary for this week gives an indication of the scale of the resources involved:
25. 19 ships totalling 78,234 tons have been reported lost by enemy action, and of these 16 ships (52,668 tons) were British. Nine British ships (44,042 tons) were sunk by U-Boats and one large Norwegian ship (18,673 tons), 3 British ships (2,392 tons) and a Belgian Trawler were sunk by mine. One British ship and a Trawler were sunk by aircraft. Thirteen ships are reported damaged by enemy action.
Protection of Seaborne Trade.
26. During the week ending noon Wednesday, the 11th December, 795 ships, including 130 allied and 12 neutral, were convoyed, and of these three are reported lost by enemy action. One battleship, one cruiser, eleven armed merchant cruisers, 43 destroyers and 30 sloops and corvettes were employed on escort duty. Since the commencement of hostilities 46,610 ships have been convoyed, of which 200 have been lost.
See TNA CAB/66/14/8