Axis submarines are credited here with roughly 8.4 to 8.5 million tons sunk in the Atlantic during the same period. That raw total came from far more submarines operating against much more shipping than the Royal Navy had at Malta. Malta's 412,575-ton figure may also be conservative because ships could be overloaded and their reported tonnage unreliable. Dividing losses by the number of boats deployed makes the U-class force at Malta and the larger submarines at Alexandria look much more effective. Gibraltar's heavily attrited S-class boats also compare well by this measure. Per-boat rates therefore put opportunity and force size alongside absolute tonnage.
Notable Point · 33:18-35:27
Measuring submarine effectiveness per boat
Comparing sinking totals by submarines deployed changes how Malta's U-class and Alexandria's T-class operations look beside the Battle of the Atlantic.