Question: Which of Tristan und Isolde and Saint François d'Assise was written first?
Context: Gottfried von Strassburg (died c. 1210) is the author of the Middle High German courtly romance "Tristan", an adaptation of the 12th-century "Tristan and Iseult" legend.  Gottfried's work is regarded, alongside Wolfram von Eschenbach's "Parzival" and the "Nibelungenlied", as one of the great narrative masterpieces of the German Middle Ages.  He is probably also the composer of a small number of surviving lyrics.  His work became a source of inspiration for Richard Wagner's opera "Tristan und Isolde" (1865). Fire and Sword ("Feuer und Schwert – Die Legende von Tristan und Isolde") is a 1982 German romance/adventure film, directed by .  It is based on the legend of Tristan and Iseult. Saint François d'Assise is an opera in three acts and eight scenes by French composer and librettist Olivier Messiaen, written from 1975 to 1983.  It concerns Saint Francis of Assisi, the title character, and displays the composer's devout Catholicism.  The world première was given by the Paris Opera at the Palais Garnier on 28 November 1983. Johanna Meier (born February 13, 1938) is an American operatic soprano.  She has been described as "one of the foremost Wagnerian sopranos of her era".  She had an international career, including fourteen years at the Metropolitan Opera and three summers singing the role of Isolde in Wagner's "Tristan und Isolde" for the Bayreuth Festival—the Festival's first American Isolde. Yseult Island is a small rocky island 0.7 nmi east of Tristan Island and 0.4 nmi north of the east point on Cape Jules.  Photographed from the air by U.S. Navy Operation Highjump, 1946-47.  Charted by the French Antarctic Expedition under Barre, 1951–52, and so named because of its twin relationship with Tristan Island.  Yseult is the French spelling of Isolde, legendary heroine incorporated into Arthurian legend and later popularized by Richard Wagner's opera "Tristan und Isolde". The Tristan chord is a chord made up of the notes F, B, D♯ , and G♯ .  More generally, it can be any chord that consists of these same intervals: augmented fourth, augmented sixth, and augmented ninth above a bass note.  It is so named as it is heard in the opening phrase of Richard Wagner's opera "Tristan und Isolde" as part of the leitmotif relating to Tristan. Ludwig Schnorr von Carolsfeld (July 2, 1836July 21, 1865) was a German Heldentenor and the creator of the role of Tristan in Richard Wagner's opera "Tristan und Isolde".  His career was curtailed by a serious illness which killed him at the age of 29, after only four performances in the role of Tristan. Tristan Island ( ) is a small rocky island 1.1 km west of Yseult Island and 0.3 km north of the west point on Cape Jules.  Photographed from the air by U.S. Navy Operation Highjump, 1946-47.  Charted by the French Antarctic Expedition under Barre, 1951–52, and so named because of its twin relationship with Yseult Island.  Tristan is the popular spelling of Tristram, legendary hero incorporated into Arthurian legend and later popularized by Richard Wagner's opera "Tristan und Isolde". Tristan und Isolde ("Tristan and Isolde", or "Tristan and Isolda", or "Tristran and Ysolt") is an opera, or music drama, in three acts by Richard Wagner to a German libretto by the composer, based largely on the romance by Gottfried von Strassburg.  It was composed between 1857 and 1859 and premiered at the Königliches Hof- und Nationaltheater in Munich on 10 June 1865 with Hans von Bülow conducting.  Wagner referred to the work not as an opera, but called it "eine Handlung" (literally "a drama", "a plot" or "an action"), which was the equivalent of the term used by the Spanish playwright Calderón for his dramas. Dalit Hadass Warshaw (born August 6, 1974) is a New York-based composer, pianist, thereminist.  Previously on the composition and music theory faculty of Boston Conservatory, she currently serves on the composition faculty at CUNY-Brooklyn College.  Her works have been performed by dozens of orchestral ensembles, including the New York Philharmonic and Israel Philharmonic Orchestras (Zubin Mehta conducting), the Boston Symphony, the Cleveland Orchestra, the Houston Symphony, the Y Chamber Orchestra, the Colorado Symphony and the Albany Symphony Orchestra.  In April 2006, her piece "After the Victory" for orchestra and chorus, was premiered by the Grand Rapids Symphony and the North American Choral Company.  Her first recording, entitled "Invocations" was released by Albany Records in 2011.  Her first piano concerto, "Conjuring Tristan," was commissioned by the Grand Rapids Symphony in 2014.  The work was inspired by Richard Wagner's "Tristan und Isolde," as well as by Thomas Mann's novella "Tristan."  The piece received its world premiere in January 2015, with Warshaw as the soloist.
Answer: Tristan und Isolde