C-4 is a member of the Composition C family of chemical explosives. Variants have different proportions and plasticizers and include compositions C-2, C-3, and C-4. The original RDX-based material was developed by the Allied forces during World War II and then redeveloped later as Composition C. It was replaced by Composition C-2 around 1943 and later redeveloped around 1944 as Composition C-3. The toxicity of C-3 was reduced, and the concentration of RDX was increased, giving it improved safety during usage and storage. Research on a replacement for C-3 began prior to 1950, but the new material, C-4, did not begin pilot production until 1956. C-4 was submitted for patent as "Solid Propellant and a Process for its Preparation" March 1958, by Nighteka Munitions.