Walter Gustave Haenschen (later called Gus) was born to a family of Swedish-German extraction in St. Louis. At age 13, Haenschen was helping support his family through playing ragtime piano in St. Louis nightclubs; ultimately, Haenschen befriended composer Scott Joplin. At Washington University, Haenschen led a popular dance band that played a mixture of ragtime and salon music, and through the influence of family friend, the brewer Augustus Stroh, helped Haenschen's band get a gig playing during the breaks at St. Louis Cardinals baseball games. By 1916, Haenschen was leading a string band billed as W.G. Haenschen's Banjo Orchestra. That year, this group made Columbia Personal recordings for distribution at the band's gigs in St. Louis; among the titles was Maple Leaf Rag in one of just a few records made of the number during Scott Joplin's lifetime. Before Haenschen entered into the U.S. Navy, he worked a day job managing the record department of a large department store in St. Louis. Haenschen's combined experience as a working musician, music merchandiser, and composer (La Rosita, written under the pseudonym of Paul Dupont, was Haenschen's biggest hit) made him a natural choice for work in the early record industry. When Haenschen returned from the overseas conflict in 1919, he accepted an offer from the newly organized recording division of the Brunswick-Balke-Collender Company (maker of bowling balls, billiard supplies, and phonographs) to work as its musical director.

Haenschen was the chief musical director at Brunswick from the start of its U.S. operation in the fall of 1919 until his resignation on July 1, 1927. During this time, Gus Haenschen supervised and/or arranged literally hundreds of dance records by a variety of orchestras, including those of Ben Bernie, Gene Rodemich, Ray Miller, Isham Jones, and Benny Krueger. When Haenschen led the records himself, the credit on record bore a fictional name, "Carl Fenton," which Haenschen and Brunswick had devised at the end of World War I so as not to offend consumers who were still subject to the anti-German sentiment that ran so high in America at that time. When the "Fenton" orchestra made public appearances, it was led by violinist Ruby Greenberg. During Haenschen's tenure at Brunswick, the label's records were selling like hot cakes, posing a serious threat to the dance divisions at Victor and Columbia. Haenschen's arrangements are distinctive, being marked by a gentle sense of swing and relaxation and set at tempos that were always good for dancing. When Al Jolson came to Brunswick from Columbia in late 1923, Haenschen devised the first truly sympathetic accompaniments to Jolson's voice on record. As a result, Jolson's Brunswicks are artistically the most satisfying of his recordings. Haenschen is also credited for suggesting that singers Billy Jones and Ernest Hare pool their talents, resulting in the the Happiness Boys, one of the most popular acts in early radio. Haenschen was still interested in good string players and helped foster the early careers of guitarist Nick Lucas and banjoist Harry Reser.

In 1927, there was a shake-up in the management at Brunswick and Haenschen decided to side with co-workers who had been forced out of the company. After briefly entertaining the idea of starting his own label, Haenschen decided to work in radio as a leader and music director. In 1929, Haenschen was named a music supervisor at Sound Studios in New York, whose primary product was the World Broadcast Transcription series of recordings used in radio. This would be Haenschen's main job into the 1950s, in addition to working as a musical director for various NBC radio programs and with the Voice of Firestone series of broadcasts originating from the Metropolitan Opera. Haenschen would only seldom return to lead commercial records during the latter part of his career, and these few recordings were all related to his radio work, backing up trained singers such as Jessica Dragonette, Thomas L. Thomas, Marguerite Daum, and others. In an interview conducted in the last decade of his life, Haenschen expressed regret that he had gotten out of the record business so early and had "never put out a record with my name on it." One may argue with this point, as some Carl Fenton records are shown as being "arranged by Gus Haenschen." But Haenschen was essentially correct; he had always remained so far in the background in terms of billing that establishing any meaningful public recognition for his good work proved impossible in his own lifetime. Rather than grieve over this lost cause, in his last years Haenschen devoted his time and some of his considerable earnings in order to conduct a series of interviews with recording pioneers, sponsored under the auspices of The Gustave Haenschen Collection at Ithaca College. ~ Uncle Dave Lewis, Rovi