2012 is the 50th anniversary of the premiere of the work in 1962. Keeping with one tradition in casting, the DSO has a Russian soprano, a German bass, and a British tenor as soloists: Olga Guryakova, Dietrich Henschel, Ian Bostridge. Peter Pears was unavailable, I hear.
As dear Wikipedia (see link above) notes:
The War Requiem, first performed on 30 May 1962, was commissioned to mark the consecration of the new Coventry Cathedral, which was built after the original fourteenth-century structure was destroyed in a World War II bombing raid on the night of 14 November 1940. The reconsecration was an occasion for an arts festival, for which Michael Tippett also wrote his opera King Priam, which premiered in Coventry the night before the War Requiem.
As a pacifist, Britten was inspired by the commission, which gave him complete freedom to choose the type of music to compose. He conceived of setting the traditional Latin Mass for the Dead interwoven with nine poems about war by the English poet Wilfred Owen. Owen, who was born in 1893, was serving as the commander of a rifle company when he was killed in action on 4 November 1918 during the crossing of the Sambre-Oise Canal in France, just one week before the Armistice. Although he was virtually unknown at the time of his death, he has subsequently come to be revered as one of the great war poets.
Here is an excerpt, at Gloucerster Cathedral, with the original cast, as it were (Galina Vishnevskaya, Dietrich Fischer-Dieskau, Peter Pears):
Here is a track from the original recording, with video added:
I could post clips of multiple performances of the whole work, but I will spare you. If you are unfamiliar with the War Requiem, I encourage you to procure a recording of the entire work, and to attend a live performance, if you can find one. If it sounds harsh on first listening, listen again. It is considered by some to be the most profund work of the 20th century. I can't say that I disagree.