Derived from the "Mousetrap" anti-submarine rocket, it was intended for use in demolishing concrete bunkers and fortifications, and saw use from August 1944.

[2] The 7.2-Inch Demolition Rocket was developed by the Physical Chemical Problems branch of the National Defense Research Committee, located at Caltech,[3] in late 1943 as a modification of the existing 7.2 in (180 mm) ASW rocket (Mousetrap) for use against heavily fortified ground targets.

Assigned to the United States Navy for development and production in July 1944,[4] An additional high-explosive rocket, the T24, was planned, but was dropped in favor of the T37.

[8] The rocket was also intended to be fired from tanks for the clearing of bunkers and anti-tank obstacles.

The initial launcher, dubbed "Cowcatcher", was mounted on the front of M4 Sherman tanks;[9] it was quickly found unsatisfactory, and was replaced by 20-round (T40 "Whiz Bang")[10] and 24-round ("Grand Slam") launchers mounted atop the tank's turret.