Whilst gardening in Pensford, two local residents made a surprising discovery – a 79-year-old, 1kg German incendiary bomb. Alongside it, they found the inert tail section of another incendiary, suggesting that additional unexploded ordnance (UXO) might still be buried nearby.

This incident serves as a stark reminder that even the shallowest groundworks can unearth historic munitions. Weighing just 1kg, incendiary sub-munitions often lacked the mass to penetrate deep into soft ground, making them more likely to remain hidden just beneath the surface for decades.

What is a 1kg German incendiary bomb?

These small yet destructive World War II-era bombs were designed with a magnesium alloy body and filled with thermite, a chemical compound that burns at extreme temperatures. Upon impact, a percussion charge would ignite the thermite, setting off an intense fire.

The standard B1E incendiary bomb made up the bulk of these bomb loads, but some variants were designed with a small explosive charge and a delayed fuse. These modified versions acted as a deterrent against early firefighting efforts, causing secondary explosions if disturbed.

Burning at temperatures exceeding 1,000°C, these bombs posed a severe fire hazard, igniting flammable materials in their vicinity. Due to their potential to cause destruction, all variants of these bombs should be treated as hazardous, not just those containing additional explosives.

Between 1940 and 1944, over a million of these 1kg incendiary bombs were dropped on Britain by Luftwaffe aircraft. They were typically dispersed via cluster bomb containers, each holding up to 620 sub-munitions. As a result, the 1kg incendiary remains one of the most commonly encountered unexploded Luftwaffe bombs in the UK today.

For a deeper insight into UXO contamination in the UK, you can explore more on our blog here.

Assessing UXO risks

The discovery in Pensford highlights the ongoing risk posed by buried wartime ordnance, even in non-military areas. Whether you’re planning construction, excavation, or landscaping, understanding the UXO risk on your site is essential.

Brimstone remains the only Ministry of Defence-assured explosive ordnance clearance and conventional munitions disposal contractor in the UK. Our expert team provides comprehensive UXO risk assessments, ensuring the safety of personnel and project timelines.

If you have a new or upcoming construction project and need your site assessed for UXO risks, reach out to our dedicated commercial team today.

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