In his famous paper

Stallings, John, On fibering certain 3-manifolds. 1962 Topology of 3-manifolds and related topics (Proc. The Univ. of Georgia Institute, 1961) pp. 95–100 Prentice-Hall, Englewood Cliffs, N.J.

Stallings proves a theorem that (roughly stated, I'm ignoring some hypotheses) says that if $M$ is a 3-manifold, then every short exact sequence $$1 \longrightarrow G \longrightarrow \pi_1(M) \longrightarrow \mathbb{Z} \longrightarrow 1$$ with $G$ finitely generated comes from a fiber bundle $M \rightarrow S^1$. In particular, $G$ is a surface group.

This is an oft-quoted theorem, but I have trouble reading the paper. Are there any expository accounts of it anywhere?