c. 1820—London, England

The Royal Artillery Band, which is comprised of 39 players, includes one alto trombone, tenor trombone, and bass trombone (Dudgeon, Keyed Bugle 29).

c. 1820–Paris, France: An anonymous illustration of a French military band includes two rear-facing trombones (see top row of below image; public domain) (Camus, Military Musicians).