The Disney bomb saw limited use by the United States Army Air Forces in Europe from February to April 1945.

[6] These enormous weapons were designed to strike close by their target, to penetrate deeply into the earth, and to cause major structural damage by the shock waves transmitted through the ground.

[8][Note 4] The Disney bomb, by contrast, was designed from the start to penetrate the thick concrete roofs of fortified bunkers.

To this end, the warhead was composed of an unusually thick steel shell containing a comparatively small amount of explosive.

The forward section was the warhead—an explosive charge of 500 pounds (230 kg) of shellite,[2] contained within an armour-piercing casing of thick steel and fitted with two British No.58 MK I tail pistol fuses at the base (i.e. furthest from the nose).

[21] He was also an enthusiastic inventor and had filed several patents pre-war, including ones for a vegetable peeling knife[22] and a bottle for fountain pen ink.

The Road Research Laboratory[Note 12] provided theoretical formula for penetration from US data on the performance of 15-inch (381 mm) shells against reinforced concrete, and the Chief Engineer of Armament Development at Fort Halstead prepared a preliminary design to present to the MAP.

Due to the Prime Minister's absence through illness, it was not until January 1944 that Churchill expressed a desire that the bomb should be considered by the committee.

[24] Terrell received support through the Air Technical Section of the USAAF, and was able to show the Admiralty a mockup under the wing of a Boeing B-17 Flying Fortress.

The Air Ministry was still opposed to its development on several technical grounds, and it took a meeting of the War Cabinet in May, which Terrell attended, to decide in its favour, giving it "P plus" priority.

As a side effect the meeting focused attention on the issue of the U-boat shelters, and the RAF were directed to make attacks on them, dropping 26 Tallboys in August 1944.

This was ideal for the purpose as the area had been captured by Allied forces in September 1944, so damage to the structure could be inspected after bomb tests.

[30][31] This was the site of two separate fortified pens used by the German navy to house their Schnellboote (fast torpedo boats, known to the Allies as "E-boats")[32] and Biber midget submarines.

[32] The pens were priority targets as the torpedo boats they protected were a considerable threat to the supply lines serving Allied forces in western Europe.

[42] Valentin's 4.5-metre-thick (15 ft) roof had already been damaged by two 10-ton Grand Slam bombs dropped by the RAF three days earlier, on 27 March.

[43] During the Eighth Air Force attack more than sixty Disneys were launched, but only one hit the target, with little effect, although installations around the bunker received considerable damage.

[44] After the bombing the Germans made limited attempts to carry out repairs before abandoning the complex; the area was captured by the British Army four weeks later.

[51] However, Watten proved too small to be a satisfactory target,[50] and the French objected to continued bombing of their territory in peace-time.

[53] This was a 1946 joint Anglo-American programme to test a range of concrete penetrating bombs against a wartime German bunker on the small island of Heligoland and the Valentin submarine pens.

A total of 76 Disneys were dropped on Heligoland, loaded with a variety of explosive charges, composed of shellite, RDX, TNT, or Picratol.

[15] A further four had been previously dropped on a bomb range at Orford Ness to test their accuracy, and to make sure none would land outside the safety exclusion zone that was set up around Valentin during the trials.

Furthermore, it was noted that the warhead of the bomb was comparatively small,[57] so a very large bunker complex such as Valentin would have required many penetrating hits to be sure of destroying all the contents.

[60] In January 2009, the body of an inactive Disney bomb, with its 500-pound (230 kg) explosive charge, was extracted from the roof of Watten bunker, by now a private museum, where it had embedded itself during one of the 1945 test-drops.