Explosive Coal and Other Disguised Sabotage Devices

Introduction to Disguised Sabotage

During the Second World War, the British Special Operations Executive (SOE) and the American Office of Strategic Services (OSS) developed a sophisticated array of sabotage devices designed to blend into everyday environments. These “disguised explosives” allowed agents and resistance members to target high-security installations by exploiting the mundane nature of industrial and domestic logistics [5]. Among the most ingenious of these was the use of explosive coal, a device that turned a primary energy source into a weapon of infrastructure destruction.

Explosive Coal: Design and Deployment

Explosive coal was specifically engineered to target steam locomotives, ships, and factory furnaces [5]. The primary objective was to penetrate relatively unguarded coal storage areas that supplied heavy security installations, bypassing the need for a direct assault on the facility itself [5].

Technical Characteristics

The SOE’s Section D developed a design consisting of a hollow shell made in two halves, crafted to mimic the appearance of a large piece of coal [3, 5]. These shells were filled with plastic explosives and equipped with a detonator, fuse, and an igniter match [5]. To ensure the device was indistinguishable from the local fuel supply, the OSS provided a “Coal Camouflage Kit,” which allowed agents to paint the shell to match the specific color and texture of the coal used in a particular region [3].

Operational Use

The device was designed for simplicity in deployment. An operative would covertly place the explosive coal in a coal bin or store [5]. Once the fuel was shoveled into a boiler or furnace, the heat would trigger the igniter, causing the device to detonate inside the firebox, leading to catastrophic failure of the boiler or engine [2, 3].

Other Disguised Sabotage Devices

The development of explosive coal was part of a wider philosophy of “irregular warfare” championed by the SOE to “set Europe ablaze,” as described by Winston Churchill [4]. This involved creating items that could be casually discarded or left in plain sight without raising suspicion.

Explosive Vermin and Household Items

One of the most notable counterparts to explosive coal was the use of dead rats filled with plastic explosives [5]. These were deployed against similar targets as the coal; agents would toss them into coal stores or leave them in factories [5]. This tactic exploited the common practice of the time, where the standard method for disposing of dead vermin was to burn them in the nearest furnace [5].

Beyond these, SOE “boffins” at laboratories such as Aston House in Stevenage produced a vast array of disguised items. These included explosives hidden within:

• Soap and clogs [4]
• Bottles of Chianti [4]
• Bicycle pumps and suitcases [4]

These items served a dual purpose: some were intended for direct sabotage, while others were used to conceal codes and intelligence for agents operating behind enemy lines [4].

Historical Context and Legacy

While the concept of explosive coal in the Second World War is well-documented, the practice of using disguised fuel for sabotage has deeper roots; similar simple devices were employed as early as the US Civil War [1].

Effectiveness and Discovery

The use of these devices saw initial success, particularly in Belgium [5]. However, the effectiveness of such covert tools often diminished once the enemy became aware of their existence. In the case of the SOE’s disguised explosives, German forces discovered the nature of these weapons after recovering a downed British plane that contained examples of the equipment [5].

Museum Collections

Surviving examples of these devices provide insight into the ingenuity of wartime sabotage. The International Spy Museum holds a collection that includes both the explosive coal device and its accompanying camouflage kit, dating from approximately 1942-1945 [3]. Additionally, archival footage filmed by Cecil Vandepeer Clarke, an SOE sabotage expert and engineer, documents the history and development of these weapons [2].