From an article in the April 26, 1943 edition of Time:

“One of the biggest song publishers is the U.S. today is the Music Section of the U.S. Army’s Special Service Division. Its monthly output runs to 1 million copies. Every month, in its Manhattan office, it culls and reprints a selection of popular tunes. Within a few weeks every U.S. Army company from North Africa to Guadalcanal is supplied with a new batch of Sheet music. A committee of top-flight U.S. entertainers (Fred Waring, Rudy Vallee, Bing Crosby, Kate Smith, Dinah Shore, Kay Kyser, Paul Whiteman, etc.) gladly act as song judges.

This venture, known as the U.S. Army Hit Kit, was started several months ago by Major Howard Bronson and Captain Harry Salter, a onetime radio musical director. The Special Services Division thought U.S. doughboys ought to have something up-to-date to sing, to provide a substitute for Army bands which are often left far behind the front. The Army has since found the Hit Kit useful in another way. U.S. forces rolling over occupied territory in tanks and jeeps make a friendly impression on native populations by bellowing such tunes as Roll out the Barrel. Which is neither a U.S. nor British tune, but Czechoslovakian.”