Developed for United States military forces in the 1950s, it was first used during the Vietnam War. The bomb consists of a cast steel case with 96 lb (44 kg) of Composition H6, Minol or Tritonalexplosive. The power of the Mk 81 was found to be inadequate for U.S. military tactical use, and it was quickly discontinued, although license-built copies or duplicates of this weapon remain in service with various other nations.
Mark 81 Snakeye fitted with a Mark 14 TRD (Tail Retarding Device) to increase the bomb's drag after release. The bomb's increased air-time, coupled with its (relatively) forgiving safe drop envelope, allowed for very low-level bombing runs at slower speed. Used commonly in the close air support role in Vietnam (prior to wider availability of GBU-series precision ordnance). Nicknamed "snake", as in the typical Vietnam support loadout of "snake and nape" (250-lb. Mk-81 Snakeye bombs and 500-lb. M-47 napalm canisters).
Tom, Gervasi (1981). Arsenal of Democracy II: American military power in the 1980s and the origins of the new cold war with a survey of American weapons and arms exports. Volume 2 (Paperback ed.). London, United Kingdom: The Book Service (TBS) Ltd. ISBN978-0-394-17662-8.