Initially the ordinance for the Bazooka came about due to some shaped charges that were acquired from the Swiss in the 1930s. After it was determined that they would not work well as grenades, a Colonel named Skinner devised a tube-shaped delivery system that aws named after an odd-shaped trombone played by Bob Burns. After trials and tests, the Rocket Launcher M1, or M1 Bazooka began manufacture in 1941 and was used in WWII as the standard anti-tank weapon of the USA.
M1 Bazooka on Wikipedia