Submarines And The Western Front

This post is a little break in the regular broadcast on current affairs...

On the question of why it took until the summer of 1944 for Britain and the USA to open a Western front against Nazi Germany, it is often claimed that the submarine attacks on Allied transport ships hindered the buildup of an invasion force and delayed the Western front two years.

I did some research, and this claim doesn't stand up to scrutiny.

The U-Boot war during WWII can be roughly separated into three phases. The first was when Britain practically stood alone, the second phase was when Britain and the USA joined forces to organise logistics and the future Western front, and the third phase was when the naval war against the Allied merchant fleet was practically lost, with only ocassional sinkings by and lots of losses for the U-boats. The end of the second phase can easily be put at May 1943, after which attacks on the Atlantic were even ceased for a few months. But the first and second phases are less clearly delineated: one could argue for the beginning of 1942, when the Allies became Allies and the opening of the Western front was promised to Stalin; or the end of 1941, when the USA entered war; or autumn 1941, when the US Congress and Senate authorised the participation of US transport ships in transatlantic military supply convoys (thereby increasing total transport capacity).

Ironically, the argument about the significance of the U-boat war rests on the same overt focus on sunk ship tonnage vs. newly built ship tonnage totals that the German leadership had. This overlooks a lot of significant details.

First, let it be noted that German captains and thus the German command significantly (in some years by 60%) overestimated their successes, but their figures get quoted unresponsibly. Or, quoted are Allied ship loss totals, which included losses to collisions, storms etc. too. (I use figures of an 1961 tally based on comparison of British and German sources by a German historian.) Second, while it is true that Allied new ship production surpassed losses to the war on their transport ships only in the second half of 1942, the merchant fleet also had other sources of growth: acquiring the ships of previously neutral countries. For example, in 1940, the Norwegian king ordered the Norwegian merchant fleet (4.2 million BRT in total) to sail into British ports - more than two-thirds did, and their volume total alone exceeded British losses until the spring of 1941. Thus in fact British/Allied transport capacity steadily grew even until the second half of 1942. Third, the decrease in transport capacity would have been only the first sign that Nazi Germany gets anywhere closer to its goal of starving Britain from its supplies - not of significant losses already.

Indeed, for the question of how much the preparation of the invasion was delayed, it's not transport capacity but trasported volume that's important - and more ignored points abound. For, while in the second phase, U-boats often sunk more than a hundred ships a month, in excess of 500,000 BRTs, this phase was also the time when U-boats were first sent out to the US coast and later the Southern seas - sinking lots of ships on coastal routes, or neutral ships (for example, Brazil entered the war on the Allied side because of such attacks) - neither of which can be viewed as even indirectly significantly impending the preparations of a European land invasion. In truth, throughout the first two phases, Nazi submarines never managed to sink more than 65-70 transport ships on transatlantic routes a month (the mean was around 40, some 250,000 BRT), equivalent to about two average convoys (the mean = to a bit more than one) - while in the spring of 1941 already, more than 50 convoys crossed the Atlantic a month!

However, what if we take the hypothetical best-case scenario, that is (1) British/Allied ship-building would have been stepped up just as much had there been no war on their transport ships, and that (2) all of these newly built and 'unsunk' ships could have been filled with materials to transport, and that (3) all 'unsunk' coastal and neutral ships would have been diverted for transatlantic transports?

According to my calculations, at no point during the second phase could transport capacity have been greater than what it was in reality by more than 20%. As for the first phase, the 'gain' of the hypothetical case would have been greater towards the end - some 30%: losses of more than 6 million BRT vs. an active fleet of more than 20 million BRT - but the aggregate transported volume 'gain' would only have been less than half of that over this period. Yet again, if we move further away from reality, and compare the two scenarios (with or without an U-boat war on the merchant fleet) had the US not joined the European war actively, Britain's war efforts would have been significantly delayed.

So as a conclusion, I think the Soviet charge that the Western front was delayed two years in the hope that Nazi Germany and the Soviet Union would weaken each other rings truer. But the argument about Churchill's fear of repeating Gallipolli also caries weight - i.e. that Churchill wanted a very thorough preparation to avoid failure, which - witness the Americans at Omaha beach - was probably necessary for victory. On the other hand, the U-boat campaign's strategic 'success' was comparable to the 'success' of Allied bomb raids on German cities, which failed to impede production significantly or break war morale.

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