  The non-equilibrium dynamics of domain wall initial states in a classical
anisotropic Heisenberg chain exhibits a striking coexistence of apparently
linear and non-linear behaviours: the propagation and spreading of the domain
wall can be captured quantitatively by \textit{linear}, i.e. non-interacting,
spin wave theory absent its usual justifications; while, simultaneously, for a
wide range of easy-plane anisotropies, emission can take place of stable
topological solitons -- a process and objects intrinsically associated with
interactions and non-linearities. The easy-axis domain wall only has transient
dynamics, the isotropic one broadens diffusively, while the easy-plane one
yields a pair of ballistically counter-propagating domain walls which,
unusually, broaden \textit{subdiffusively}, their width scaling as $t^{1/3}$.
