What kind of things should trombones do in marching bands in the following case?

Question

I'm trying to write some simple stuff (kind of) for brass marching band and not entirely happy with how it sounds. (But this might be because of the MuseScore sounds.)

I have a trumpet playing the main melody and main voice. A cornet is following the trumpet, harmonizing the whole melody below.

I don't know at all what trombones usually do in marching bands. I'm talking about tenor trombones. I thought of doing fewer notes, and emphasizing the first note of each measure to create a kind of inverted chord sound. Also, I'm not sure how long the notes should last or how they should be sustained in general.

Answer 1

You can give the trombones everything you want:

1. The rhythmic harmony with the horns

2. A counter melody or imitation of the main tune together with other tenor instruments

3. Play the bass line with the bass

4. In the trio section they also can play the tune with tenor or Eb-horns.