Dies Irae--Day of Wrath--is the name of the greatest of all medieval Latin hymns, the Gregorian Chant of the Dead and a part of the Requiem Mass. It is a powerful description of Judgment Day and a prayer to Jesus for mercy. It was probably written by Friar Thomas of Celano (who died circa 1256), a Franciscan who knew St. Francis.
Since the sixteenth century, Dies Irae has been used as the inspiration for many great works of religious music, including the Requiems of Bach, Mozart, Brahms, and Verdi, Berlioz's Symphonie Fantastique, Lizst's Totentaz, Tchaikowsky's Third Suite, and Saint-Saens's Symphony No. 3. Rachmaninov used it repeatedly, in Isle of the Dead, Symphonic Dances, and other compositions. The plainsong clearly had great personal significance for him.
More recently, in 1967, the noted Polish classical composer Krzysztof Penderecki named his famed "Auschwitz Oratorio" Dies Irae. "A memorial to the victims at Auschwitz, Dies Irae allows the singers and players to improvise according to their talents and abilities. The chorus recites words, rather than singing them, and the instruments are the framework for the rhythm and pitch. It was first performed on the grounds of Auschwitz in 1967."
If you've seen Citizen Kane, you've heard Dies Irae. Bernard Herrmann used Dies Irae as the basis of the Kane theme. At the end of the film, when you hear the thrilling, anguished music that accompanies the tragic burning of Kane's Rosebud sled--that's Dies Irae.
You can hear a beautiful rendition of Dies Irae here.
When America was attacked on September 11, many said it was our nation's dies irae. A Google search of "September 11" and "dies irae" will produce a surprising number of results. In the aftermath of the attacks, several composers produced symphonies entitled Dies Irae for U.S. memorial services.
Here is a selection of sites that deal with the hymn Dies Irae:
CIA September 11 gets right to the point and quotes Dies Irae's lyrics (reproduced, with a slight modification, at the top of this page) to begin an article about 9/11, the CIA, and globalization.
The Dies Irae discusses the powerful influence this great plainsong has had on Western music.
A short entry, but very good.
The Encyclopædia Orbis Latini entry.
The Catholic Encyclopedia. Very detailed.
The Wikipedia entry. Excellent.
A side-by-side Latin/English translation.
A literal English translation, courtesy of the Franciscan Archive.
Another wonderful side-by-side translation.
The Society of St. Pius X in Manitoba, Canada offers this translation, with musical score.
Thomas Babington Macaulay (1800-1859), the great British historian and statesman, produced this translation of the lyrics of Dies Irae.
Even wild, pagan, wicked Oscar Wilde was moved to comment on Dies Irae in a poem, Sonnet on Hearing the Dies Irae Sung in the Sistine Chapel--though his response is typically anti-Christian.