Vietnam War: Forest Fire as a Military Weapon - Paperless Archives

SECRET
This report contains the findings and conclusions of Project EMOTE and is presented in final fulfillment of ARPA
Order 818.
FOREST FIRE EFFECTS
When considering forest fires as a potential weapon. certain advantages and limitations must be kept clearly in mind.
The greatest single superiority factor of fire as opposed to other damage-causing agents, is that under the proper circumstances
fire is self-propagating. A relatively large area can be covered with a minimum expenditure of ordnance. The
burning of the U Minh Forest in March and April 1968 resulted in a burned-over area of more than 1000 square miles
from an expenditure of 20 aircraft sorties and 36 naval gunfire support missions (see Appendix A). The damage caused by
this fire was equivalent to that of a 20 megaton nuclear device. On the other hand, the greatest single disadvantage to the
use of forest fires as military weapons is that they are totally weather dependent. Thus their use against troops (in the
move must be opportunistic rather than planned, and successful forest incendiary operations are most likely when
directed at fixed bases, or at least semi-permanent targets such as potential ambush sites.
The overwhelmingly important result of forest fires from a military point of view is visibility enhancement and
cover denial. Despite the use of an array of sophisticated sensors for improving aerial intelligence capability, an analysis of
tactical air strikes in South Vietnam during fall of 1966 showed that there were 35 strikes on "suspected" troop locations
for every strike on a "known" troop location. 7 - 1 Equally revealing is an analysis of Australian/UK ground engagements in
Borneo. Malaya. and Vietnam which showed that over 75 percent of all enemy targets were encountered in forest cover
regardless of whether the attack was initiated by enemy or friendly forces. N
In addition to removing vegetative cover, all forest fires can be expected to destroy some supplies. Intense fires will
also produce some casualties. The extent of damage will depend on th• type of forest fire. There are four generally
recognized forest fire types:
1. Creeping ground fire. The creeping ground fire is the least intense and least damaging of the four fire types.
As the name implies, ground fires burn in the leaves and litter of the forest floor without consuming standing trees of
shrubs. Ground fires spread at rates varying from a few inches per minute to a maximum of about 4 feet per minute with
flames less than 2-3 feet high. Although these fires do not consume trees or bushes, they do heat their stems at the
groundline and can kill the smaller and thinner barked species. Within a day or two the leaves wilt on affected plants.
Thus horizontal visibility is enhanced at eye level by a factor of 2-3 in situations where brush or vines normally limit
visibility. Since the larger trees that make up the top layer of cover generally have larger, more fire-resistant stems, they
are relatively unaffected by ground fires. Consequently, vertical visibility is not changed after ground fires.
Even the lightest ground fires will cause some damage, particularly to munitions, unless precautions have been taken
to piotect loose stores by raking the area around them clean of all leaves and debris. Three of the six Vietnamese forest
fire raids studied by Project EMOTE resulted in initiation of light ground fires (Sherwood Forest, Pink Rose I, Pink Rose
Ill). Despite the fact that none of these fires burned any appreciable amount of foliage, and that the initial incendiary
7_ Zwemer, H. A. Tactical Air Strikes in South Vietnam - Fall 1966. CIRADS I1 Proc. Vol 1i, Part I pp. 109-119.
June 1967. CONFIDENTIAL.
N_ The ABA Firepower Study Group. Some statistics 'f counterinsurgency operations. CIRADA 11 Proc. Vol. II, Part 2,
pp. 3-31. June 1967. SECRET.
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