In March 1943 Lüth set out for a second patrol off South Africa and in the Indian Ocean, in particular the waters around Mauritius. This patrol lasted 205 days (23 March 1943 – 14 October 1943) making it the second longest of the war. (The longest combat patrol of World War II was 225 days in length, which was achieved by Eitel-Friedrich Kentrat as commander of the .) Lüth sank 10 ships totaling on this patrol, which turned out to be his last. While at sea he was promoted to "Korvettenkapitän" on 1 April 1943. Later that month, he received news that he had been awarded the Knight's Cross of the Iron Cross with Oak Leaves and Swords.