Sinfonia da Requiem, Op. 20, for orchestra is a symphony written by Benjamin Britten in 1940 at the age of 26. It was one of several works commissioned from different composers by the Japanese government to mark the 2,600th anniversary of the founding of the Japanese Empire (taken to be 11 February 660 BCE). The Japanese government rejected the Sinfonia for its use of Latin titles from the Catholic Requiem for its three movements and for its somber overall character, but it was received positively at its world premiere in New York City under John Barbirolli. A performance in Boston under Serge Koussevitzky led to the commission of the opera Peter Grimes from the Koussevitzky Music Foundations.
The Sinfonia is Britten's largest purely orchestral work for the concert hall. It was his first major orchestral work that did not include a soloist and, according to musicologist Peter Evans, marks the peak of his early writing in this idiom. Unlike many of Britten's works from this time, it has remained popular and continues to be programmed on orchestral concerts.
The symphony is in three movements played without a break, and a performance usually lasts around 20 minutes. Britten's analysis, quoted in the Los Angeles Philharmonic Orchestra's program notes, reads:
I. Lacrymosa. A slow marching lament in a persistent 6/8 rhythm with a strong tonal center on D. There are three main motives: 1) a syncopated, sequential theme announced by the cellos and answered by a solo bassoon; 2) a broad theme, based on the interval of a major seventh; 3) alternating chords on flute and trombones, outlined by piano, harps and trombones. The first section of the movement is quietly pulsating; the second is a long crescendo leading to a climax based on the first cello theme. There is no pause before:
II. Dies irae. A form of Dance of Death, with occasional moments of quiet marching rhythm. The dominating motif of this movement is announced at the start by the flutes and includes an important tremolando figure. Other motives are a triplet repeated-note figure in the trumpets, a slow, smooth tune on the saxophone, and a livelier syncopated one in the brass. The scheme of the movement is a series of climaxes of which the last is the most powerful, causing the music to disintegrate and to lead directly to:
III. Requiem aeternam. Very quietly, over a background of solo strings and harps, the flutes announce the quiet D-major tune, the principal motive of the movement. There is a middle section in which the strings play a flowing melody. This grows to a short climax, but the opening tune is soon resumed, and the work ends quietly in a long sustained clarinet note.
The headings of the three movements are taken from the Roman Catholic Mass for the dead, but the composition has no liturgical associations. Britten described the movements respectively as "a slow, marching lament", "a form of Dance of Death" and "the final resolution". All its movements have D as their tonal center.