  A four-dimensional topological field theory is introduced which generalises
$B\wedge F$ theory to give a Bogomol'nyi structure. A class of non-singular,
finite-Action, stable solutions to the variational field equations is
identified. The solitonic solutions are analogous to the instanton in
Yang-Mills theory. The solutions to the Bogomol'nyi equations in the
topologically least complicated $U(1)$ theory have a well-behaved (covariant)
phase space of dimension four---the same as that for photons. The dimensional
reduction of the four-dimensional Lagrangian is also examined. Bogomol'nyi
$U(2)$ solitons resembling the intermediate vector bosons $Z_o$, $W^\pm$ are
identified.
