Norman A MacLeod
Inventor/developer of the M18 Claymore directional anti-personnel mine.
Following the massed Chinese attacks during the Korean War, Canada and the United States began to develop projects to counter them.
Canada fielded a weapon called the "Phoenix" landmine that used the Misznay-Schardin effect to project a spray of 0.25 inch steel towards the enemy. The cubes were embedded in five pounds of Composition B explosive. It was too large to be a practical infantry weapon and was relatively ineffective with a maximum effective range of only 20 to 30 yards (20 to 30 meters).
Around 1952 Norman MacLeod at his company the Explosive Research Corporation began working on the concept of a small directional mine for use by infantry. It is not clear if Picatinny took the concept from this Canadian weapon and asked Norman MacLeod to develop it; or if he came up with the idea independently and presented it to them.
MacLeod's design, the T-48, was broadly similar to the final M18A1, although it lacked many number of the design details that made the M18A1 effective. It was accepted into Army service as the M18 Claymore and approximately 10,000 were produced. It was used in small numbers in Vietnam from around 1961, but it wasn't until the arrival of the improved M18A1 that it became a significant weapon.
The M18 Claymore mine.
The M18 was 235 millimeters long and 83 millimeters high with a plastic case with three folding spike legs on the bottom. An electrical blasting cap for triggering the mine was inserted through a small hole in the side. Internally the mine consisted of a layer of 340 grams of C-3 explosive (the forerunner of C-4 explosive) in front of which was laid an array of 0.25 inch steel cubes. In total the mine weighed about 1.1 kilograms, and could be fitted with an optional peep sight for aiming. [2]. It lacked the later version's iconic "FRONT TOWARD ENEMY" marking. The mine was planted in the ground using its three sharp legs and was aimed in the direction of enemy approach and then fitted with an electrical blasting cap. The mine was then triggered from a safe position, preferably to the side and rear.
The mine was barely more than a prototype and was not considered a "reliable casualty producer" with an effective range like the Phoenix of only 90 feet (30 meters). [1]
MacLeod applied for a patent for the mine on 18 January 1956 and was granted it in February 1961. [3] The patent was later the source of a civil court case between MacLeod, the Army and Aerojet who proceeded to develop the design further. MacLeod's case collapsed when photographs of the German Trenchmine prototype were produced as evidence of prior art.
The drawings for MacLeod's 1956 patent application.
