The M18 Hellcat is a tank destroyer that was used by the United States Army in World War II and the Korean War. It was the fastest U.S. armored fighting vehicle on the road. This speed was attained by keeping armor to a minimum, using the innovative Torqmatic automatic transmission, and by equipping the relatively light vehicle with the same main gun used on some variants of the much larger Sherman tank. Entering service in 1944, the M18 served primarily in Western Europe, but was also present in the Pacific. M18 strength in the European Theatre of Operations varied from 136 in June 1944 to a high of 540 in March 1945. Losses totaled 216. Kills claimed were 526 in total: 498 in Europe, 17 in Italy, and 11 in the Pacific. The kills-to-losses ratio for Europe was 2.3 to 1 and the overall kill to loss ratio was 2.4 to 1. M18s were "...not primarily used for tank fighting, but were committed more often to improvised roles, usually direct fire support for infantry." The Hellcat was the most effective U.S. tank destroyer of World War II. It had a higher kill to loss ratio than any other tank or tank destroyer fielded by U.S. forces in World War II.