  The origin of thermal and quantum entanglement in a class of
three-dimensional spin models, at low momenta, is traced to purely topological
reasons. The establishment of the result is facilitated by the gauge principle
which, when used in conjunction with the duality mapping of the spin models,
enables us to recast them as lattice Chern-Simons gauge theories. The thermal
and quantum entanglement measures are expressed in terms of the expectation
values of Wilson lines, loops, and their generalisations. For continuous spins,
these are known to yield the topological invariants of knots and links. For
Ising-like models, they are expressible in terms of the topological invariants
of three-manifolds obtained from finite group cohomology -- the so-called
Dijkgraaf-Witten invariants.
