Merry Christmas! Although Messiah is, strictly speaking, not Christmas music, having been composed for Lenten performances, today we most often hear it at Christmas.
Handel used trombones to great effect in two of his oratorios, Saul and Israel in Egypt, both first performed in 1738. Apparently he did not have access to trombones in any later year; he considered adding trombones to two later oratorios, not including Messiah, but soon abandoned the effort.
Unlike most other music of his time and earlier, Handel’s did not suffer posthumous neglect. The Concert of Ancient Music, founded in 1776, actually had a rule that it would perform no music unless it was at least 20 years old. There was hardly any music with authentic trombone parts that came within these limits, but Adam Carse reports that W. Greatorex, its secretary and librarian, “an incorrigible arranger and adder of accompaniments, was kept fairly busy gilding lilies.” The orchestra regularly included clarinets, four horns, and three trombones.
Not only did English audiences continue to enjoy his oratorios, they even came into vogue in Vienna. Mozart reorchestrated Messiah, among other Handel works, to bring them up to date. Typical of Mozart’s own church music, his Messiah arrangement includes three trombones (1789).
The English apparently did not use a standard orchestration. The great Handel commemoration of 1789 assembled a large chorus and orchestra, including every instrument Handel had ever used. Sources differ, but the orchestra had either three or six trombonists, who all played other instruments when there were no trombone parts. That does not mean that they played trombone only for Saul and Israel in Egypt. Various accounts of the performance mention trombones in several other pieces.
After the three performances originally scheduled, the king commanded that some of the music be repeated in two more concerts. Commenting on the repetition of Messiah on the second of these, Charles Burney, the event’s official historian, noted some significant differences in the manner of playing it: “Another new and grand effect was produced to-day in the Hallelujah, and last Chorus, “Worthy is the Lamb,” by the introduction of the tromboni, which were not used in these Choruses, on the former occasion.”
The Times of London advertised at least twelve Lenten performances of Messiah between 1797 and 1800 “assisted by the Trombones and Double Drums, used at Handel’s Commemoration at Westminster Abbey.” As far as I can tell, Mozart’s orchestration was not yet known in England. Its eventual discovery did not keep meddlers from adding to it, as this complaint from the Times about the 1846 Birmingham Festival attests:
The brass instruments (two serpents, an ophicleide, and three trombones included) completely murdered the choruses, “the Lord of hosts,” and “Hallelujah.” Surely Mozart has done as much with Handel’s score as is necessary, and, indeed, permissible; the noisy unmeaning additions of loud instruments by Greatorex and others, only serve to transmogrify the sublimity of Handel into mere rant; and moreover, the object of increased power is not obtained, since those choruses in which the score of Handel remains untouched, except by the mastery and considerate hand of Mozart, are twice and loud and brilliant as those which have been smothered under a weight of brass, &c., by incompetent and injudicious meddlers. The intrusion of two serpents, three trombones, and an ophicleide, into the score of such a complete masterpiece as the Messiah, is absolutely ridiculous; and it should be the duty and wish of judicious conductors to restore Handel to his primitive integrity.
“Greatorex and others” appears to include John Smithies, one of the most active trombonists in London at least from the early 1820s into the middle of the 1840s. Apparently, most later conductors continued to use the same arrangement for the rest of the century. The Times summarized a lecture about the subject in 1899:
Gresham Lectures in Music.–The last two of the series of four lectures given by Sir Frederick Bridge on Handel’s Messiah were exceedingly interesting; that on Thursday could not fail to be most amusing throughout, since it dealt with the incredible “improvements” of Mozart’s additional accompaniments, and with the added trombone parts of a certain Mr. Smithies, who perpetrated an appalling number of dissonances and harmonic errors, which apparently have been retained down to the present day.
Perhaps by that time, someone started to make an effort to clean up the standard score and parts, but performances with a thousand choristers and orchestras with instruments Handel never heard of continued until the attempt to find authentic performance practice started in earnest after the Second World War.