The Disney Bomb, also known as the Disney Swish, officially the 4500 lb Concrete Piercing/Rocket Assisted bomb was a rocket-assisted bunker buster bomb developed during the Second World War by the British Royal Navy to penetrate hardened concrete targets, such as submarine pens, that could resist conventional free-fall bombs. Devised by Royal Navy Captain Edward Terrell, the bomb was fitted with solid-fuel rockets to accelerate its descent, giving it an impact speed of and hence the ability to penetrate of solid concrete before detonating. The name is attributed to a propaganda film produced by the Walt Disney Studios, that provided the inspiration for the design.