  A lagrangian which describes interactions between a soliton and a background
field is derived for sigma models whose target is a symmetric space. The
background field modifies the usual moduli space approximation to soliton
dynamics in two ways: by introducing a potential energy, and by inducing a
Kaluza-Klein metric on the moduli space. In the particular case of the Skyrme
model, this lagrangian is quantised and shown to agree with the leading
pion-nucleon term in the chiral effective lagrangian, which is widely used in
theoretical nuclear physics. Thus chiral perturbation theory could be
considered a low energy limit of the Skyrme model.
