no there isn't - but what if a player decides that he wants his 1 move to be a march move? there's also nothing to say that a single move has to be a tactical move - and having made 1 march move he then cannot shoot....
so there's a bit of a gap in the rules about what sort of move you have made if you make exactly 1 move - if it starts within 400p it has to be a tactical move (unless only enemy skirmishers, troops facing away within 400, etc) - but if it starts outside 400 it can be eitehr tactical OR march - there's no guidance that it has to be specifically one or other