Operation Sherwood Forest
Operation Hot Tip

In December 1965, the Joint Chiefs of Staff requested that the Secretary of Defense initiate research to determine the feasibility of measuring the flammability characteristics of forests and jungle growth, modifying flammability so that vegetation would readily support combustion and developing measures to destroy large areas of forest or jungle growth by fire. The research was subsequently conducted by the Forest Service of the Department of Agriculture, under sponsorship of the Advanced Research Projects Agency (ARPA) through ARPA Order 818.

Interest in this concept of operations had come in part from a fire bombing raid, code-named Operation Sherwood Forest, against the Boi Loi Forest, 25 miles west of Saigon in late March 1965. In support of Operation Sherwood Forest, 78,800 gallons of herbicide were delivered between 22 January and 18 February 1965 by Detachment 1, 315th Troop Carrier Group. The initial strike, to be conducted by B-52 bombers loaded with M35 incendiary bombs, was scheduled for 3 March 1965. There had been no rain for 5 days prior and no rain was forecasted. On 3 March 1965, with the aircraft already in the air, the weather forecast changed to include thunderstorms. The operation was cancelled and the aircraft returned to Guam.

The operation was rescheduled for 11 March 1965 and was successfully conducted on that date. The raid did not result in any appreciable destruction of forest cover, the concept evoked considerable interest. In September 1965, Commander in Chief, US Pacific Command (CINCPAC) requested that the Joint Chiefs of Staff take action to expedite the development of a device capable of destroying large areas of jungle or forest growth by fire. In December 1965, the Joint Chiefs of Staff by JCSM-862-65, requested that the Secretary of Defense initiate programs to determine the feasibility of dehydrating jungle growth to the point where such material would support combustion, and to initiate development of operational means for determining the specific conditions under which there was the greatest probability of destroying jungle or forest growth by fire. This in turn led to APRA Order 818 and Project Environmental Modification Techniques (EMOTE).

A team of US Forest Service technicians in the field of forest fuels began work on this effort in January 1966. The USAF, in coordination with CINIPAC, was authorized to conduct in the Republic of Vietnam (RVN; South Vietnam) a test of a fire ignition source. The USAF Chief of Staff advised of the MACV plan to conduct a jungle-burn operation in RVN, recommended to CINCPAC that the BLU-29/B delivered by B-52 aircraft be evaluated as the fire-ignition source in the test. On 19 January, the MACV J3 suggested that since ARPA had been directed by the Secretary of Defense to initiate tests on burning jungle foliage, and as the Joint Research and Test Activity (JRATA) had a technical team to plan, advise, and evaluate such tests, that JRATA be the responsible office for the test project of burning Chu Pong mountain forest. The MACV J3 further indicated that although this project was essentially a test it could yield substantial operational benefits if successful. Suggested phases for the operation were: Phase I, defoliation of target area; Phase II, weather evaluation to determine time for ignition; Phase III, air operations; and Phase IV, evaluation.

The test, designated Operation Hot Tip, was initiated on 24 January 1966. In late February 1966, MACV asked Strategic Air Command (SAC) about the feasibility of destroying the jungle cover on the Chu Pong Mountain area in Pleiku province. Again defoliants were used to assist in making the foliage flammable. By 23 February 1966, 22,000 gallons of Agent Orange defoliant had been delivered. In March 1966, SAC B-52s dropped 172 tons of 750-pound M35 incendiary bombs (27 bombs carried in each B-52) in 2 separate missions, codenamed Hot Tip I and Hot Tip II. The first of these operation was launched on 11 March 1966. The initial report stated that the test was an outstanding operational success, but apparently only a qualified technical success. All phases of the test were conducted under optimum conditions at precise times and with spectacular delivery accuracy, but heavy flames were not observed and fire storms did not develop. Vertical visibility was reported to have substantially improved, however. The results were sufficiently successful that an expanded program of research to develop operational criteria was pursued.