The possession of radar and the breaking of Italian codes, particularly the Boris Hagelin C38 cipher machine used by the "Regia Marina", further contributed to British success. In November 1941, the supply of the Axis forces in Libya from Italy, had been interrupted by Force K, which had destroyed several Italian convoys (most notably the Duisburg convoy) and the loss of nearly 70 percent of the supplies sent to Libya, including 92 percent of the fuel. Force K based at Malta, and ships from Alexandria, intercepted an Axis convoy "Maritza" and "Procida", escorted by two Italian torpedo boats, sailing from Greece to Benghazi of on 24 November. The convoy was about west of Crete when the merchant ships were sunk by two British cruisers and two destroyers, the torpedo boats making off once it was certain that the ships were doomed. The loss of the cargoes led the German command to report that the fuel situation of the "Luftwaffe" in North Africa was critical.