Developed during 1942 by the California Institute of Technology (Caltech), under the direction of Charles Christian Lauritsen,[2] in response to a requirement by the United States Navy for a rocket capable of being launched from landing craft to provide fire support during amphibious landings, the 4.5-Inch BBR was an improved version of the Mousetrap anti-submarine rocket system, using the Mousetrap's Mk 3 rocket motor mated to a 20-pound (9.1 kg) general purpose aerial bomb.

[3] An impact fuse was mounted in the nose of the rocket, with an annular fin assembly providing stability.

[3][4] First test fired on 24 June 1942, further tests in August proved sufficiently successful for the Navy Bureau of Ordnance to place an initial order for 3,000 Beach Barrage Rockets;[5] the weapon was introduced into combat service that November, during the invasion of northern Africa.

[3] Fired from 12-round launchers[6] and capable of being fitted with either the standard high explosive or a white phosphorus warhead,[3] approximately 1,600,000 examples of the BBR were built;[7] although the rocket proved inaccurate in service, it was widely used, and was highly regarded by members of the amphibious forces.

[9] The 4.5-Inch BBR also saw use as an improvised ship-to-ship weapon, as well as being launched from ground-based launchers; it is credited with the first ship to be sunk by another purely by rocket attack, occurring near Ormoc in December 1944.