Olivier Messiaen (French pronunciation: [mɛsjɑ̃]; December 10, 1908 – April 27, 1992) was a French composer, organist, and ornithologist. He entered the Paris Conservatoire at the age of 11 and numbered Paul Dukas, Maurice Emmanuel, Charles-Marie Widor and Marcel Dupré among his teachers. He was appointed organist at the church of La Trinité in Paris in 1931, a post he held until his death. On the fall of France in 1940 Messiaen was made a prisoner of war, and while incarcerated he composed his Quatuor pour la fin du temps ("Quartet for the end of time") for the four available instruments, piano, violin, cello, and clarinet. The piece was first performed by Messiaen and fellow prisoners to an audience of inmates and prison guards. Messiaen was appointed professor of harmony soon after his release in 1941, and professor of composition in 1966 at the Paris Conservatoire, positions he held until his retirement in 1978. His many distinguished pupils included Pierre Boulez, Yvonne Loriod (who later became Messiaen's second wife), Karlheinz Stockhausen, Iannis Xenakis and George Benjamin.