HC MK 1 COOKIE BOMB “Cookie”

The HC 4,000 lb Mk I (High Capacity) was a British World War II “blockbuster” bomb designed to deliver maximum blast effect. It featured a thin-walled steel casing that allowed approximately 75% of its total weight to be explosive filler—typically Amatol. Unlike armor-piercing bombs, the HC Mk I was intended to flatten buildings and infrastructure through overpressure rather than penetration.
It was commonly fitted with a Pistol D.A. No. 13 Mk I nose fuze, which featured vane blades that rotated in free fall to arm the fuze. In addition, the bomb carried two Pistol No. 30 Mk II body fuzes, which were non-vane impact pistols serving as auxiliary or backup detonation mechanisms. The bomb was deployed by Avro Lancaster bombers during strategic bombing campaigns, including the Heligoland raid on April 18, 1945.
The nickname “Cookie” for the HC 4,000 lb. Mk I bomb came from RAF ground crews and airmen who thought the bomb resembled a giant cylindrical biscuit or cookie—flat-faced, round, and oversized.