Explosives Used by SOE Saboteurs

Historical Context

During the Second World War, the Special Operations Executive (SOE) was tasked by Winston Churchill to “set Europe ablaze” by supporting resistance movements and conducting irregular warfare behind enemy lines [2]. A critical component of this mission was sabotage—the deliberate destruction of enemy infrastructure, transport, and supply lines to hamper the Axis war effort. To achieve this, the SOE required explosives that were not only powerful but also malleable, concealable, and capable of being deployed in diverse environments, from ship hulls to industrial furnaces [1, 3, 4].

Development and Research

The creation of these devices was the work of “boffins” and engineers operating out of specialized research centers. Key locations included the SOE laboratory at Aston House in Stevenage, Hertfordshire, and MD1 at Whitchurch [2, 3]. One of the prominent figures in this development was Cecil Vandepeer Clarke, a British engineer and sabotage expert who worked across several weapon research and development centers to refine the tools used by agents in the field [1, 3, 4].

Key Explosive Types and Devices

Plastic Explosive

Plastic explosive was a fundamental component that enabled the creation of many other sabotage devices [1]. Its primary advantage was its malleability, allowing agents to shape the explosive charge to fit a specific target, such as molding it into a ring shape to be applied to a steel plate [1]. This flexibility made it far more versatile than rigid explosive blocks for field operations.

The Limpet Mine

Developed by Military Intelligence (Research) between late 1939 and 1940, the limpet mine was designed for maritime sabotage [4]. Developed by Stuart Macrae and Cecil Vandepeer Clarke, these mines utilized magnetic strength to attach an explosive charge directly to the hull of a ship [4]. While initial designs were large, they were refined into various marks and types over the course of the war, including smaller versions used against metal plates [4].

Specialized and Concealed Sabotage Tools

To avoid detection, the SOE developed “ingenious” devices that concealed explosives within everyday objects [2]. These allowed agents to smuggle materials into occupied territories or plant charges in plain sight:

• Explosive Coal: Designed to be placed inside coal stores, furnaces, and fireboxes, this device was intended to explode within the heating systems of enemy infrastructure, causing significant internal damage [3].
• Everyday Objects: Documents reveal that agents were equipped with explosives hidden in a wide variety of items, including soap, clogs, bottles of Chianti, bicycle pumps, suitcases, and even artificial rats [2].

Operational Use and Impact

These tools were deployed by a variety of operatives, including SOE agents and Allied partners such as the Free French Air Force, who were trained in the application of these devices [4]. By providing resistance movements with the means to conduct precise sabotage, the SOE could disrupt the enemy’s logistics and communications without requiring the heavy artillery or large-scale troop movements of a conventional army.

Museum Collections and Records

Much of the visual evidence regarding these devices survives through archival footage held by the Imperial War Museum (IWM), including films recorded by Cecil Vandepeer Clarke demonstrating the preparation and application of plastic explosives and limpet mines [1, 3, 4].