The Oak Leaves, as they were commonly referred to, were based on the enactment of 3 June 1940. In 1941, two higher grades of the Knight's Cross were instituted. The enactment of 28 September 1941 introduced the Knight's Cross of the Iron Cross with Oak Leaves and Swords and the Knight's Cross of the Iron Cross with Oak Leaves, Swords and Diamonds. At the end of 1944 the final grade, the Knight's Cross of the Iron Cross with Golden Oak Leaves, Swords, and Diamonds, based on the enactment of 29 December 1944, became the final variant of the Knight's Cross authorized. The Oberkommando der Wehrmacht (Supreme Command of the Armed Forces) kept separate Knight's Cross lists for the Heer (Army), Kriegsmarine (Navy), Luftwaffe (Air Force) and Waffen-SS. Within each of these lists a unique sequential number was assigned to each recipient. The same numbering paradigm was applied to the higher grades of the Knight's Cross, one list per grade. Of the 32 awards made to servicemen whose last name starts with "U", four were later awarded the Knight's Cross of the Iron Cross with Oak Leaves and one presentation was made posthumously. Heer members received 23 of the medals, none went to the Kriegsmarine, seven to the Luftwaffe, and two to the Waffen-SS.