In a regular orchestra the violin takes an important role. Why is it that in marching bands there are no strings usually? To give some context I'm working on a march composition and I like strings because they add a nice cinematic effect but I'm a bit iffy since a regular marching band doesn't have it. Maybe in compositions there are no rules though?
Actual marching bands don't have strings - I'm sure you could extend this list of reasons:
- Where would string players put sheet music?
- String instruments are expensive and fragile. Whilst you can buy a professional trumpet for a couple of grand, that doesn't buy you a professional quality violin. And although you can repair a dented trumpet, a snapped neck or crushed cello body is much more serious.
- Volume - you'd need lots of strings to match the volume of the wind instruments.
- The bumps and so on of marching would put the strings out of tune.
- Brass instruments are waterproof. Violins aren't.
...and so on.
So although you could write for Marching Band and strings you're unlikely ever to get it performed by actual people.
Instead I'd suggest writing an orchestral march, to be performed by a seated orchestra in a concert hall. There are lots of marches or march-influenced pieces in the orchestral repertoire that you could plunder for orchestration colours.
As Brian Thomas pointed out, there's a huge difference between a marching band and a musical composition called a "march."
Marching bands are called that because, well, they march. Or in the case of Yale Univ., gyrate madly around the field. You won't find string instruments (mostly), double-reeds, and a few other oddball instruments in a fielded band.
A composition that's a "march" may well feature percussion, keep a strict binary beat (i.e. no 3/4 or 5/4 unless you have mutants with extra legs), and generally evoke pageantry.
Because stringed instruments are fragile and not very loud. And, traditionally, just because they don't. In the same way that brass bands don't have woodwinds and string quartets don't have trombones.
If marching bands wanted strings, they'd find a way. Either some harness contrivance, or they'd put them in the 'pit' with the heavy percussion.
And there's nothing to stop you writing for a non-marching concert band plus strings.
But you're right, if you're writing for a particular MARCHING band, it would be sensible to omit strings.
(Anyway, there are, sometimes)