Chemical retaliatory plans during World War II called for using mustard gas (H) and phosgene (CG) aerial bombs (the most successful chemical agents used during World War I). Though scientists had discovered many new agents, these agents were generally extensions of the knowledge gained during World War I. For example, the British "secret weapon" of the time was high-altitude, aerial-spray attacks using runcol (HT), a mustard gas variant with a 60:40 mixture of H and O mustard (T). A revolution in chemical warfare was dependent on German development of nerve agents.

In 1936, at the German Leverkusen pesticides laboratory of I. G. Farben, Dr. Gerhard Schrader discovered tabun (GA). (1) The military utility of Schrader's discovery became clear when a single drop on a laboratory bench produced enough vapor to sicken him and a coworker. After performing a demonstration for the chemical warfare section, German army officials provided Dr. Schrader a laboratory at Wuppertal-Elberfeld in the Ruhr Valley to continue his work.

German scientists went on to discover sarin (GB), soman (GD), ethyl satin (GE), and cyclohexyl sarin (GF). In 1939, GA was manufactured in a pilot plant at Munster-Lager. By 1942, there was also a production plant in Dyerfurth-am-Oder and another plant under construction.

The Chemical Warfare Service (CWS) may have known of the German interest in nerve agents as early as 1941. The United States investigated similar compounds, notably phosphorus (III) fluoride diisopropylflurophosphate (PF3), but concluded that they were only usable as eye irritants. In 1943, the British interrogated a German chemist who had firsthand knowledge of sarin. The Germans wrongly interpreted British censorship of pesticide research as an indication that the Allies were aware of the nerve agents. However, the secret of German nerve-agent research was not apparent until the Allies began to overtake German chemical dumps in April 1945. (2)

The Chemical Corps continued to study nerve agents and create more analogs after World War II. A national effort to create an arsenal with nerve agents did not receive priority until the Stevenson Ad Hoc Committee and the Korean War. Another impetus was the decision by the Air Force to be completely capable with chemical and biological weapons by 1954.

GA: The Interim Nerve Agent

Chemical warfare plans for the European theater depended on a chemical arsenal located in England. Within 24 hours, Army Air Force units could conduct attacks on tactical and strategic targets. Although these plans initially called for large-scale strategic employment, by September 1944 the Allies had scaled back plans to include only immediate tactical support for the Normandy invasion. (3)

The retaliatory plans for the Pacific theater were more problematic. Despite requests from the CWS in the mid-Pacific, appropriate stocks were not located closer than the California coast. This meant a retaliatory response time of 30 to 60 days. More importantly, plans for chemical retaliation against Japan called for quantities of chemical weapons that were not available. A survey of the zone of interior (Asiatic-Pacific and European-Mediterranean theaters) showed that only 855,000 persistent and 271,000 nonpersistent bombs were available. The retaliatory requirements against Japan called for 5,181,000 persistent bombs and 776,000 nonpersistent bombs. The CWS believed that the German arsenal could fill the gap and embarked on a crash program to evaluate the utility of these weapons.

The United States had captured 23,000 tons of GA in aerial bombs and 6,000 tons in 10.5-centimeter projectiles. The Army Air Force could deliver the aerial bombs without modification, but the 10.5-centimeter projectiles were too wide for Army 105-millimeter artillery. The CWS sent 3,000 tons of aerial bombs and 5,000 tons of projectiles to Edgewood Arsenal, Maryland, for further evaluation.

The German ordinance was punched and drained at Edgewood Arsenal to evaluate GA in the 4.2-inch mortar rounds and the M70 (E46) aerial bomb. Field trials showed that standard bursters were too small to disseminate GA due to the low volatility of the agent. Only 10 to 20 percent of the agent was dispensed as aerosol or vapor. Furthermore, the CWS initially believed that the [LCt.sub.50] (median lethal dosage) of GA was about 800 milligram-minute per cubic meter (mg-min/[m.sup.3]). The conclusion was that GA was useful for harassment but was not suitable for chemical retaliation. (4)

During the Cold War (1950s), the British believed that the Soviet Union had standardized the use of GA. The United States estimated the Soviet stockpile at about 18,000 metric tons of GA in 1952, in addition to about 120,000 tons of older chemical munitions. The implications that Germany's nerve-agent production facilities and scientists had fallen into Soviet hands at the end of World War II was not lost on anyone. (5)

Replying to a request from the Commander in Chief of the Far East for a chemical capability by 7 June 1952. the Joint Chiefs of Staff stated that it would provide World War II vintage chemical weapons within six months and newer chemical weapons (such as nerve agents) after 1954. (6) When the Far East Air Force requested guidance on chemical employment against North Korea in January 1953, the discussion was exclusively on using World War II weapons containing CG, cyanogen chloride (CK) (a blood agent), and mustard gas, with particular interest in CK to penetrate protective masks.