Gaston Louis Christopher Borch (8 March 1871 – 14 February 1926) was a French composer, arranger, conductor, cellist and author. His works include orchestral music, opera and music for silent films. He played and conducted with orchestras in Europe and the USA.
Borch was born in Guînes, Pas de Calais, France. His mother, Emma Hennequin, a pianist and soprano, was a friend and pupil of Jules Massenet, whom she met when he stayed at her father's boarding house, and with whom she is known to have performed. His father, Christopher Wolner Borch, was Norwegian. Borch's sister Frida was also an accomplished pianist.
Borch played the cello. He studied for three years with Massenet in France, with Jules Delsart and also at the Valand School of Fine Arts in Sweden. During the 1890s he spent time variously as conductor of the Christiania Orchestral Society and the Central Theatre in Christiana (now Oslo), and was also a visiting conductor in various European countries. His reported conducting credits include the Amsterdam Symphony Orchestra; Brussels Opera Orchestra; Société Symphonique, Lille; Crystal Palace Orchesta, London; Harmonie Royale, Antwerp; Gewerbehaus Orchestra, Dresden; and the Musikforeningen of Bergen (1898-1899).
Between 1898 and 1906 he worked as a musician and conductor in the USA. He was engaged as a cellist with the Theodore Thomas Orchestra in 1899, worked with the Chicago Symphony Orchestra and Syracuse University, and was principal cello of the Pittsburgh Symphony Orchestra 1903-1906, under Victor Herbert. In 1901 Borch's patent application for a device to amplify the vibrations from a piano indicates he was living at the time in Duluth, Minnesota. He spent some time in Europe in 1906 as conductor of the Lausanne Symphony Orchestra. He conducted the Grieg Jubilee Concerts in New York in 1907. He was for a time a faculty member of the Pennsylvania College of Music.
Between 1916 and his death Borch was a prolific composer of photoplay music; short, stock pieces designed to evoke a particular mood. These were then selected and combined by musicians to create an appropriate scene-by-scene score for the silent films, or "photoplays", they accompanied live. In 1918 he published his Practical Manual of Instrumentation, a technical manual for musicians which included several chapters on the adaptation of works written for larger orchestras to smaller ensembles, such as those working in picture houses. By 1925 he was sufficiently prominent in the field to be described as one of "the three "B's" of picture music", along with Maurice Baron and Irénée Bergé — "a formidable trio of expert writers".
In 1920 Borch was reported as attempting to establish a grand opera company in Boston, Massachusetts. Borch returned to Europe in 1921, settling in Sweden, where he was an arranger and musical contributor to the score of The Saga of Gosta Berling (1924), starring Greta Garbo. On 1 January 1925, the first day of radio broadcasting in Sweden, Borch led the Skandia Cinema Orchestra in Sweden's first broadcast of orchestral music.
Borch married Rose Alice Gluckauf in July 1900 in St. Paul, Minnesota. His wife was a soprano who had previously taught at the Raff Conservatory in Frankfurt, Germany and who studied with Julius Stockhausen and Jenny Hahn. She taught music at what is now Millikin University in Decatur, Illinois from 1913 until 1922, when she filed for divorce from her husband on the grounds of desertion and bigamy.
- Silvio (1897), a one-act opera premiered on 7 March 1898, with libretto by Borch and O. A. Smith; a sequel to Cavalleria Rusticana. 
- Ostenfor Sol, a "fairy opera"
- Geneviève de Paris (1906)
- Incidental Symphonies - Used in the scores of The Cat and the Canary (1927) and White Zombie (1932)
- Misterioso Infernale (1916) - "Gruesome" section used in the score of Tarzan's Revenge (1938)
- Poeme Symphonique - Used as the theme for the 1920 silent film Madame X
- Practical Manual of Instrumentation. The Boston Music Company, 1918.
- "Composers biography - Bm-Bo". Dolmetsch online. Retrieved 9 November 2012.
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- "L'enseignement de la musique". Les Archives du Pas-de-Calais. www.archivespasdecalais.fr. Retrieved 30 October 2012.
- Who's Who in Music and Drama 1914, H.P.Hannaford and Hines, D.(eds) New York, H.P. Hannaford, p.47
- Mason, Daniel G. (1917). The Art of Music : a comprehensive library of information for music lovers and musicians, Volume 11. New York: The National Society of Music. p. 58.
- "A listing of all the musicians in the Chicago Symphony Orchestra". www.stowkowski.org. Retrieved 30 October 2012.
- "Piano attachment - Patent 700726". United States Patent Office. Retrieved 30 October 2012.
- Altman, Rick (2004). Silent Film Sound. New York: Columbia University Press. p. 305. ISBN 0-231-11662-4.
- "World of Music". Brooklyn Standard Union. 5 April 1925. p.12
- "The World of Music". The Etude Magazine. Retrieved 10 November 2012.
- "Gösta Berlings saga/del I". Swedish film database. Swedish Film Institute. Retrieved 30 October 2012.
- "Historia: Sveriges Radios Symfoniorkester". Sveriges Radios. Retrieved 30 October 2012.
- St Paul Globe, Minnesota, 6 July 1900 p 10.
- Millidek Yearbook: Class of 1920. Millikin University. 1920.. Cited at www.e-yearbook.com.
- "Faculty List". Millikin University. Retrieved 6 January 2014.
- Decatur Review. Decatur, Illinois. 11 January 1922.
- San Francisco Call. April 1 1898, p.6 Accessed 19 October 2013
- Flury, Roger (2001). Pietro Mascagni: A Bio-bibliography. E-book: Greenwood Publishing. p. 60. ISBN 9780313296628.
- The Duluth Herald. 30 October 1920. p. 10