Despite the qualified successes of Operation ‘Crusader’, Britain was faced with a disastrous turn of events in early 1942. The entry of Japan to the war had compelled a redistribution of force to the Far East, while some key British losses and new in-theatre German commitments had further redefined the Mediterranean balance of power. Chapter 5 outlines how the British were forced to adopt a defensive posture throughout the theatre, as their gains from ‘Crusader’ were rapidly reversed. As the Axis then advanced into Egypt, Malta was subjected to an intense aerial siege and came perilously close to being starved into submission. The difficulties in conducting anti-shipping operations during this period were numerous. Yet in a reversal of the thesis advanced by historians such as van Creveld and Gladman, the chapter demonstrates that significant sinkings (of over 300,000 tons) were achieved during this period. The continued attrition was greatly troubling for the Axis, contributing to a shipping shortage that was to reach crisis point later in the year.

Chapter 4 starts with the Mediterranean receiving a new level of recognition in British strategic priority during the August–December 1941 period, becoming the primary effort. Moreover, the anti-shipping campaign was promoted to a prime position in operational priority for the Navy and Air Force, with a corresponding dedication of forces to the task. Coupled with this was an increase in the pace of learning and the refinement of tactical procedures. This led to greatly increased levels of sinkings over August–December, which coincided with a new major British offensive in North Africa: Operation ‘Crusader’. These sinkings successfully denied Axis forces in Cyrenaica the necessary fuel and ammunition to either launch their own planned offensive or to resist the British advance, including the loss of 92 per cent of the fuel shipped in November. Furthermore, the increased levels of attrition meant that sinkings were now greatly outstripping the Axis replenishment capability through new construction or other means. This was the first clear example of the dual effect of the anti-shipping campaign: one operational affecting the war on land in North Africa, and one attritional, undermining the Axis ability to conduct any form of warfare in the Mediterranean. It caused serious concern among the Axis commands, leading to the adoption of new countermeasures, which were to have a major impact in the following year.