The Month the Tonnage War was Lost

It’s debtable whether or not the Germans ever came close to winning the tonnage war in World War II. I personally don’t think so but more numbers would need to be collected including the construction records of Allied shipyards not in North America as well as a determination of how much shpping tonnage Britain would have needed to stay alive. However, after collecting the merchant shipping tonnage built by Canada and the United States during the Second World War and comparing that to what I have for Allied merchant shipping losses, it doesn’t seem likely. These 2 countries alone accounted for 37.7 million gross registered tons of shipping. What this number does not account for is the amount of shipping that became available to the Allies when the United States entered the war as well as any of the new construction that happened outside of North America. That, obviously, requires a bit more work to include.

In the meantime, the first chart above compares the cumulative gains (new construction) and losses for the Allies for each month of the war. The two North American countries began to build ships faster than they could be sunk in Spetember, 1942 when 713,204 tons of new merchant shipping was delivered while 500,881 tons was lost due to war. With one exception, in every month from then on until the end of the war, Canada and the United States (the latter accounting for 93% of total war time production) easily replaced Allied losses. The German submarine arm’s Black May in which 41 of its boats were lost had yet to happen and was just the final nail in the coffin for the Germans.

Even so, it wasn’t until December 1943 that all Allied shipping losses since the beginning of the war were replaced with new construction (below).

Belgian Merchant Shipping Losses in World War II

*The Belgian merchant ship Bruxelles, 5,085 tons, sunk on June 9, 1942*

Belgium was a relatively minor player in the Second World War, both on land and on the sea. At the start of the war in September 1939, it boasted a merchant fleet of only 472,182 tons – well behind the UK, the undisputed world leader in shipping at the time with 16.6 million tons. In the period of September 1939 to May 1940 before Belgium was invaded by the Germans and the country joined the Allied cause it had already lost close 30,000 tons of shipping to accidents, mines and German torpedoes (even though it was officially neutral).

When Belgium surrendered to the Germans on May 28, 1940 only a small part of its merchant fleet fell into German hands – about 71,000 tons – while the majority – 358,000 tons – continued to serve the Allies. The Germans steadily whittled away at this disadvantage throughout the war so that by the end of the war, only about 108,000 tons of Belgian shipping in Allied control remained afloat. Of the 71,000 tons the Germans had captured, only 21,000 tons managed to survive the war. In the end, only 27% of the Belgian merchant fleet that existed at the start of the war survived to the end.

The sankey chart below provides a breakdown of the status of the Belgian fleet during the course of the war.

Submarine Activity during World War II

Submarines were the single greatest cause of vessel sinkings during the Second World War – about 34% of the total 20,000 ships that were sunk. The Germans in their U-boats accounted for 2,955 of these vessels and collectively they totaled over 14 million tons of shipping. Less well known is the US submarine war against the Japanese. American submarines accounted for 1,994 vessels with a tonnage of 5.6 million. Further down the list was the UK who accounted for 1,625 vessel sinkings of 1.5 million tons. The Japanese, surprisingly, accounted for only 187 vessel sinkings of less than a million tons.

It is worth noting a couple of things about these numbers:

Not all ships listed in the database have a tonnage value. Records for the western Allies tend to be better and more complete and these were often the victims of German submarine attacks. Japanese records – the target of US and UK submarines in many cases – are less complete.
Many of the vessels sunk by US submarines were small vessels (less than 20 tons) including fishing vessels and small junks in use by the local population (See the records for USS Blenny, for instance).