Naming his invention after the famous Scottish two-handed Claymore sword, Norman MacLeod applied the German-Hungarian anti-personnel mine research of World War II to a mine intended to counter Chinese human wave attacks during the Korean War. Introduced into service in 1954 as the M-18, Mac Leod’s original model lacked many of the features that made it so effective in Vietnam. The M-18 directional anti-personnel mine consisted of 340 grams of C-3 explosive attached to a concave array of metal cubes. It used an electrical blasting cap as a detonator, rested on three small folding spike legs and weighed about 2.4 pounds. The user planted it in the ground, aiming the mine’s flat front plate toward the enemy’s expected axis of approach and then stringing the electrical detonating wire back to his “firing position” some 5 to 20 meters behind and to the side of the mine. Its fragmentation pattern proved disappointing during operational testing, but some 10,000 were produced, with a number sent to Vietnam in 1960.
The M-18 was soon supplanted by the more effective M-18A1, in which more powerful and less corrosive C-4 replaced the C-3. Also, 1/8-inch soft steel ball bearings replaced the hardened steel cubes, and epoxy was used to hold the balls against the explosive. The mine’s flat front was curved in consonance with the explosive, improving the fragmentation pattern and the blast effect. Two pairs of scissor legs replaced the original three, the firing side was clearly labeled, and it could be aimed almost vertically. Early models had a simple peep sight, but most used a knife blade sight. The fragmentation pattern covered 30 degrees either side of the firing azimuth. Maximum effective range was about 100 meters, but 50 meters was optimal.
Besides base defense, Claymores could be used for a variety of purposes, including ambushes. One or more Claymores could be detonated on “command” by the operator, either individually or together; deployed individually as a land mine triggered by trip wire, pressure release device or other sensor system; or fired by a short-timed fuse or timing device to impede pursuit. The enemy captured many Claymores and used them as well, primarily as booby traps, even planting them in trees and along landing zones to use against helicopters. The Claymore remains a powerful and effective tactical weapon, used by several nations.
Originally published in the October 2009 issue of Vietnam Magazine. To subscribe, click here.